Leo's passive skill
Solution 1:
With his passive, the speed of all monsters, both enemies and allies, is capped at Leo's speed value and leo moves first.
For example if all monsters have 200 total speed and leo has 120 speed, then all monster will have 120 speed, but Leo will move first. The speed of all monsters immediately change.
And no, there is no way to, in my knowledge, turn off a passive skill.