Typically, this will wait until you've unlocked the Stygian Guard and have access to Spell Weakness and other powerful spells. Either one stack of Spell Weakness and a spell like Crpyt Builder dealing at least 60 damage naturally, or multiple stacks to lower the requirements.
However, there are a few other ways to get this early, such as the Hellhorned Battering Ram, where it would need to be used on a floor with at least 30 armor across all units, or a powered-up Awoken Restoration Detonation healing for 30 damage.