Mystery +1,+2: hits 9 target in the field (+1), chaos on selected target (+2)

Mystery y,y+1: gain prompt, damage reduced by 40(y) - 15(y+1) %, removes super armor (y), chaos on selected target (y+1).

Std +1,+2: high chance of knockdown + chaos (+1), chakra stealing up to 100 (+2)

Chase1 +1: ignores a certain amount of defence and resistance.

Chase1 y: increase mystery cd by 1 round. Can only be used once.

Chase2 +1: 10 combos, hits 4 targets + poison.

Chase2 y,y+1: 20 combos, hits 3 target + chaos on a random target (y), on 2 random targets (y+2).

Passive1 +1: before each action in the round... Can be used 2 times each turn.

Passive1 y: gain a stacking +10% atk / nin for each debuffs cleared.

Which one in particular?

Consider that he gain his immunity only after being hit (which means that either you put him in pos 1 with higher ini or he'll be combo'ed). His defensive stats are low, so he can be blitzed easily, even with an over-tuned kit.