If the health of this creature is negative, this creature dies BEFORE it attacks.
With Antimatter, it dies once its negative attack is switched to negative defense.
Liquid Shadow works by subtracting 1 health every time. For example:
9|1 Fortuna. Opponent plays Liquid Shadow on it. Your turn.
9|1 Fortuna attacks, deals 9 damage, heals owner for 9 damage (vampiric) and dies because it loses 1 health. Does not get to switch stats because it's dead.
1|9 Fortuna. Opponent plays Liquid Shadow on it. Your turn.
1|9 Fortuna attacks, deals 1 damage, heals owner for 1 damage (vampiric) and becomes 1|8. Switches to 8|1. Your next turn:
8|1 Fortuna attacks, deals 8 damage, heals owner for 8 damage (vampiric) and dies because it loses 1 health. Does not get to switch stats because it's dead.