yeah, some issues i noticed with colossus slayer:

1. Colossus slayer applies even when opponent is at full health: it's description states that it doesn't apply when the opponent is at full health.

2. Colossus slayer doesn't apply when using hunter's mark: If you use hunter's mark, you don't get colossus slayer damage.

3. Colossus slayer damage is not added when making off-hand attacks: If your first hit of the round is with your off-hand, you will not get colossus slayer damage. Also, if you make an off-hand attack first, and main hand attack second, colossus slayer won't apply to your main hand attack either. (I was using the Loviatar dagger in offhand that Blesses on successful hits, so I was making my offhand attack first)

4. Colossus slayer damage added to 'knock unconscious': didn't verify this, but if so it makes this Action essentially unavailable to you.

5. Colossus slayer damage doubles during critical hit: don't think this is supposed to be the case?