Brief

The length of time rewound increases as you concentrate; each standard action, you reach back further, spending 1 Mana each time.

In round 1, you turn back time 1 round (6 seconds). Each round thereafter, you turn it back 10 times as much. Thus:

Desired Rollback Amount	Number of Std Actions / Mana Cost
1 round	1
1 minute	2
10 minutes	3
1 - 1.5 hours	4
10 hours - 1 day	5
2 - 7 days	6
1 - 9 weeks	7
1 - 2 years	8
20 years	9
200 years	10
2,000 years	11
20,000 years	12
200,000 years	13
2,000,000 years	14
20 million years	15
200 million years	16
2 billion years	17
20 billion years	18
200 billion years	19

Effects are permanent. Does not work on creatures (at this rank). Only works if all of the object (or its remains) are at hand.