Initiative
Short, short version
No turns. Everybody just goes whenever they want.
- When two or more people want to go at the same time, roll Initiative within that group to determine the order.
- When you declare that you're taking an action, you can take one or more actions, as you desire. Any unused actions remain viable for the rest of the round--you could use them later for other purposes, or use them all up front.
- If someone else takes an action that you want to contest, and you haven't gone yet, you may attempt to counter them by taking an action. This works just the same as if you'd been trying to act at the same time as someone else, in that you roll opposed Initiative checks. However, you have the advantage of knowing what they intended to do and countering it specifically.
- If the action you're interrupting with is faster than the one you're interrupting, you get advantage on the Initiative roll. Bonus and move actions are faster than standard actions, and free actions are faster than bonus/move.
- This concept of interrupting an action with another action is separate from the concept of Readying an Action. You can still do that, and when that is in play, you don't have to worry about opposed Initiative checks; a readied action always interrupts the trigger action.
Inspiration
If you have Inspiration, you may expend it to turn any bonus or move action you're capable of taking into a reaction, thus obviating the need to win an Initiative check, and enabling you to react if you've already used your actions (but not your reaction).