In general, the difficulty of an encounter can be measured by the sum of all Build Points of the enemies, compared to the sum of all Build Points of the PCs.

(Note: so far, only the 100% figure has been tested)

What does this mean? Well, here's an example:

• You have a party of 5 PCs with 50 BP each (5th-level).
  • Their total BP is 250.
• Thus, the "hard" target is 250 BP.
• You could construct a Type 1 encounter vs 25 monsters with 10 BP each.
• You could construct a Type 2/3 encounter vs 1 monster with 250 BP.
• You could construct a Type 4 encounter vs 1 monster with 150 BP, backed up by minions totaling 100 BP.

There is a lot more nuance than that, of course, to be discussed in each encounter type.

The classic "minion battle". In System 7, the concept of Damage Threshold means that even high-level characters are vulnerable to attacks by low-level characters. Sure, a single goblin's arrow will hardly ever fell a 20th-level wizard...but if there's a 1-in-100 chance, and there are 100 goblins, well...that's interesting.

The default rules call for high lethality and easy hits when no defensive action is taken. However, cover, concealment, movement, and many other simple tactics are available to dramatically improve defense, without requiring any special feats or powers. In other words, enemies just standing around can expect to die very fast, while those using cover, spreading out, using surprise, etc, will fare far better. A DM who throws minions on a battle map in big chunks without any cover is handing the encounter to the PCs and wasting their time.

Now, how does one create such an encounter? Well, these types of encounters are often heavily map-based; the environment will provide huge defensive advantages, as well as interesting possibilities (hazards, devices, etc), so the DM should spend most of his/her time working on that.

Thus, the monsters themselves should be very simple, and there should only be a few types (but there should almost always be more than one type). The common types are:

Grouping

There are more ways to group than just to throw everything at the PCs all at once. A properly setup and run encounter of Type 1 will be quite difficult for them. That isn't always desirable as such; not to mention, there should always be several ways to win. Thus, other grouping options:

In any scenario where multiple groups of enemies might combine, such as the typical dungeon scenario where monsters in nearby rooms might "aggro" when they hear noise, it makes sense to create this entire encounter, then chunk the enemies into smaller groups--patrols, garrisons, etc. The rule of thumb: if they could recombine into one large group within a couple of rounds, they are really all just one big group.

By doing this, you're creating the possibility that the PCs will defeat the enemy by targeting their subgroups without alerting other subgroups, presumably by employing stealth, surprise, and other clever tactics. Thus, you reward cleverness with easier encounters, and the possibility remains that non-clever parties will pull much larger, nastier groups.

Digging In

When designing such encounters, don't just consider terrain. If the enemies have been encamped for some time, they will have had ample opportunity to optimize the environment for their own defense. They might construct walls, chokepoints, murder holes, etc. They will have time to set up traps, siege weapons, and other weapons slow to deploy.

How does one handle such a thing? Well, to be very brief:

• Traps have a BP cost when used in such an encounter. They also have an appropriate level.
• Siege weapons are just very large Weapons. They can have more RP put into raw power, offset by RP discounts for being oversized an unwieldy.

Example

Suppose you're desigining a Type 1 encounter with a target of 250 BP. Specifically, it's a clan of goblins who have claimed a cave as their warren. You might do as follows:

• 10x Goblin Warrior (Soldier, 5 BP each), 50 BP
• 10x Goblin Archer (Artillerist, 5 BP each), 50 BP
• 3x Goblin Shaman (Controller, 15 BP each), 45 BP
• 5x Worg (Brute, 10 BP each), 50 BP
• 5x tripwire trap (3 BP each), 15 BP
• 1x firepit trap (10 BP), 10 BP
• 1x Goblin Chieftain (30 BP), 30 BP
• Total BP: 250
• Bonus: 25x Goblin Noncombatant (1 BP), 25 BP

The warren is laid out thus:

• The entrance is protected by 5x Archer and 5x Warrior.
  • The archers are behind a makeshift pallisade of sticks proving 90% cover, with arrowholes allowing shots in various arcs covering about 75% of the approach. There are a few trees and rocks for the PCs to hide behind along the way, but the area is largely open. The archers will shoot the nearest targets to themselves, lacking discipline beyond that. If all PC targets are behind cover, they will ready to shoot the first one they see break cover.
  • The warriors carry wooden tower shields which lock together for 90% cover when immobile. If the PCs hide behind cover, the warriors will advance to flush them out. Otherwise, they will plug the entrance (the only access to the area behind the pallisade), attacking with spears from behind their shield wall.
  • Loose, dry straw has been set up all about the approach, and numerous torches are available to the goblins. The torches are behind them, so they do not interfere with their vision; however, PCs looking at the entrance will be dazzled by the bright light. The warriors can hurl the torches, causing the straw to ignite; the flames burn anyone in the vicinity, and spread randomly into adjacent squares...a useful tool for smoking out PCs hiding in cover.
• Beyond the entrance is a narrow, winding corridor, trapped with 2x tripwire trap.
• Winding through the entire interior of the cave are three separate patrols, each with 1x Warrior, 1x Archer, and 1x Worg. They move at their own pace, up and down the length of the shafts, sometimes randomly doubling back, etc. The Worgs have Scent.
• Beyond that is an animal warren, in which the PCs will find 2x Worg, accompanied by 2x Warrior, 2x Archer, and 1x Shaman. They might be caught unprepared and resting if the PCs were slick enough; otherwise, they will ready for defense, pushing a prepared pair of wooden spiked walls into place over the entrance, creating a narrow chokehole which a medium creature can crawl through as a full-round action (losing all active defenses), while exposed to fire from within; alternatively, PCs might try to destroy one of the two walls (HP 500, DR 10) or push it out of the way (Str DC 20 to push it over; std action, provokes, no active defense, suffer 3d6 piercing damage from the spikes, Agility DC 20 to avoid falling atop it and suffering more spike damage while being prone).
• Beyond the warren is another narrow hallway, this one with 3x tripwire trap. It branches off to one side, while the larger trunk points straight ahead.
• To the side is a treasure room. The room is blocked off by a heavy stone (full-round action, DC 23 to move one square, causes loud noise which alerts nearby patrols). Pushing it two squares into the room reveals access to the room itself, though those unaware (Perception DC 20, or 25 if pushing; 5 less if area is well lit) will not see that they are revealing a firepit trap. Simply pushing the stone forward is sure to drop the attacker into the pit, spilling many firepots and burning the fool alive.
  • There are no enemies in the treasure room, but there is a secret door from the Cheiftain's Chamber that allows goblins to drop in from above.
  • The goblins do not push the stone to gain access; the shamans chant Earth Magic which moves it as needed. They then place a plank across the firepit trap to avoid it, and return it to the Main Chamber when done.
• From the main line of the second corridor, the PCs can reach the Main Chamber. This is where the goblins gather to eat, sleep, cavort, etc. It contains a number of goblin noncombatants, as well as serving as the rallying point for any alerted, surviving goblins who are aware the PCs violated the Animal Warren.
  • It is possible the PCs took out each patrol and garrison stealthily, leading all the way up to this point. If so, their arrival comes as a complete surprise, and they will find only the Chieftain, two Shamans, and the Noncombatants. Should this happen, the Chieftain orders the Noncombatants to make a desperate Last Stand and join the fight. The Shamans empower them as best they can, and summon elemental guardians to aid them.
  • However, if the PCs got past the Animal Warren, an alarm will sound, and any remaining patrols will converge on the Main Chamber. Large stones will be pushed in front of the entrance. If they are pushed out of the way, firepots will be hurled into the openings. Meanwhile, the Noncombatants will be ushed into the Chieftain's Chamber, which will be sealed by Earth Magic. The goblins will bet on repelling the assault, or die in the attempt...the roof is collapsible, if the Chieftain and Shamans work together, which will kill everyone inside, PC and Goblin alike.

In this example, a single Type 1 encounter becomes an entire dungeon, or at least one level of a dungeon.

The idea of a Type 2 encounter is to invert the complexity of the Type 1; instead of many enemies, there are few, or (often) only one. Instead of the enemies dying quickly and easily to individual attacks, the Type 2 enemy is extremely hard to kill, or even injure. Its attacks are oversized, presenting near certainty of death if they hit.

Classic examples might include: a cave troll, a heavy military vehicle, or perhaps a magical being such as a demon or dragon.

A simple way to design this encounter would be to take the BP target and make a single monster of that BP. However, this will rarely be suitable; such a creature will have numbers vastly outside the reach of PCs, and will be far too complex to run properly. Many such enemies are quite simple (a tank, or a cave troll), and have no need of 500 BP worth of powers, feats, and skills.

So how does one empower such a creature without dumping on the BP? Simple...by increasing its Scale. In short:

What is "Scale"? Well, it's an abstract concept, but for one, it lines up almost perfectly with Size, as in Vehicle Size. A human with 50 BP, otherwise mortal, might climb into a Huge vehicle (Size +2 relative to PCs), and thus achieve Scale 2; his vehicle will have much higher DT, HP, and Damage, and will thus multiply his own BP effectiveness.

If you happen to be using a Vehicle, the actual rules are covered in Vehicles. But there are other ways to do it. (In Oathkeep, for instance, a Monster is always at least Scale 1; part of it is a size increase, but the majority of the numeric bonus is just from Scale).

As a rule, you should always explain why a monster has a Scale other than 0. Nothing is quite so jarring as a goblin with 50x more HP than he should have, for no apparent reason. Merely being "high-level" or "badass" does not qualify as an explanation--that is easily covered by the existing build system (see Type 4, or just make a character using BP). The huge bonus to HP and DT cannot be duplicated with the normal build system...it is not available simply because one killed many orcs.

Being a vehicle is a good excuse. Being of magical nature is also good. Most sizable monsters, with or without magic, can justify such power, such as the ever-popular cave troll, or of course a dragon.

Secondary Actions

Whether a vehicle, giant monster, etc, a Type 2 encounter's primary attack (be it a breath weapon, a giant club, or a tank's main gun) benefits from a sizeable damage bonus, and is often an area attack as well, possibly inflicting siege damage. In short, the primary weapon is designed to fight enemies of similar Scale, so puny PCs are no match for it.

However, such weapons are often slow, perhaps on a Recharge instead of At-Will. To rely on the primary weapon alone would make the vehicle/monster vulnerable to swarming by small attackers. Thus, secondary actions.

Each "secondary action" represents a bonus std and a bonus swift action. This is similar to System 6's elite and boss haste; however, it cannot be used for the primary weapon. Instead, these actions are used for other attacks which do not benefit from a Scale bonus to damage or effectiveness.

A vehicle might sport turrets with smaller guns, better suited for picking off swarms of small attackers. A dragon sports his claws, tail, and wings.

Of course, not every conceivable Type 2 encounter would sport such things. Thus, the secondaries can be "cashed in" to gain minion-level assistants. Each secondary can be cashed in for 25% of the total BP cost; usually, this is used to build smaller enemies, as in a Type 1 encounter.