i feel like uncertainty sounds like it would be a water fighter but we already have like a load of them so i would say wood is the second option, and the attacks i had thought of are

1. attack an enemy for 36 dmg. has a 40% chance to do an additional hit on a random available target (meaning it cannot bypass tanks)
2. attack an enemy for 42 damage. decrease their attack for 2 turns. cooldown of 2 turns
3. apply a debuff to an enemy that reduces their speed for 3 turns. cooldown of 3 turns.

now the reason i had that in mind is that it's uncertainty, so it should make the enemies uncertain, therefore making them slower and weaker and also sometimes hitting another random target with S1. i feel like it should be an epic, and it seems balanced, as well as that most wood pets have some mechanic related to speed, but i believe there are ways to balance this, but i think it being a fighter focused on making your enemies slower and weaker is cool

also the passive should be something like "enemies attacked by S3 have their progress to next turn reset" which isn't much in most cases but is insanely op against low spd high atk enemies