Does Irelia Fervant get +1 Might if Cull the Weak is countered?
No, Irelia, Fervent does not get +1 Might if Cull the Weak is countered.
According to the official ruling for Cull the Weak (FAQ #8619):
- Cull the Weak uses the structure "Each player kills a unit they control," which does not count as "choosing" or "targeting" for the purpose of triggering abilities like Irelia's.
- Because the selection is programmatic and made by multiple players as part of the spell's resolution, it does not trigger "when you choose" abilities.
Furthermore, regarding the interaction with countering:
- Even if Cull the Weak were a card that did trigger Irelia (e.g., a spell that specifically said "Choose a unit, kill it"), if that spell were countered, it would be removed from the chain and would not resolve (Rule 412.1.a).
- However, per FAQ #636, if a spell did trigger Irelia upon being played (when the target is chosen), that trigger would already be on the chain and would resolve even if the original spell were countered.
In this specific case, because Cull the Weak does not "choose" or "target" Irelia in the first place, her ability does not trigger regardless of whether the spell resolves or is countered.