Improved Initiative (Combat)Source PRPG Core Rulebook pg. 127 (Amazon)
Your quick reflexes allow you to react rapidly to danger.
Benefit: You get a +4 bonus on initiative checks.Source Pathfinder Unchained pg. 123 (Amazon)
Before rolling initiative, you can spend 10 stamina points to use 20 as the number rolled.
Mythic Improved InitiativeSource Mythic Adventures pg. 67 (Amazon)
You leap into the fray with speed and confidence.
Prerequisites: Improved Initiative.
Benefit: The bonus on initiative checks granted by Improved Initiative increases by an amount equal to your tier. This bonus stacks with the bonus from Improved Initiative. In addition, instead of rolling initiative, you can expend one use of mythic power to treat your roll as a natural 20.