This is good for dealing damage to neutral creatures with a powerful attack stack, but in Fortress battles, it's much better to have several powerful units. Otherwise, if they inflict Implosion on your stack, you can lose the battle immediately. A simple Blind spell can also cause a lot of problems.

If you're playing Inferno and want to specialize in Demonology, you usually eliminate all units from levels 1-4. It's best to have units with artifacts that increase HP, and include Eye, Medusa, Basilisk, and other similar creatures.