If my opponent plays Cull the Weak and I kill one of my units with the spell, can I play Immortal Phoenix from my trash?

Ruling: No, you cannot play Immortal Phoenix from your trash when you kill one of your units with your opponent's Cull the Weak. The condition requires you to kill a unit with your own spell.

Nuances:

• The current core rules don't explicitly cover this case, but the FAQ addresses it
• Updated core rules will explicitly define "kill a unit with a spell"