Magebane Lizard’s ability resolves before the spell that caused it to trigger. It resolves even if that spell is countered.

Noncreature spells that were cast before Magebane Lizard entered the battlefield count. If Magebane Lizard enters the battlefield after a player has already cast a noncreature spell in the same turn, that spell will be counted by Magebane Lizard’s triggered ability if that player casts another noncreature spell that turn.