Using Decisive Strike against Vecna will cause your character to be softlocked.

VeilofPeculiarity

If you use Decisive Strike against Vecna, you will get stuck in the wiggling/struggling animation and be unable to do any actions, effectively softlocking your character. This persisted through hook states, forcing me to leave the match.

Steps to reproduce that I know:

1: Equip Decisive Strike

2: Go against Vecna

3: Get hooked to activate Decisive Strike

4: Get downed and picked up by Vecna

5: Use Decisive Strike

You should end up in the wiggling animation and be unable to do actions.