[Tuidjy]

Master Enslave does not have the penetration to affect all of the opposing army.
In my last game, I was casting it (among others) with an Astral 12 (native) Seraph,
with an effective astral of 18 (boosters, banner, and shield) and penetration + 4.
Most of the enemy's heavy hitters would resist it, and we would have our little
battle afterwards... make sure that the enslave casts before your army-wide buffs,
so that your new converts do not die from the battlefield-wide enchantments.

Of course, against one of my opponents, who was relying on troops to breach my
castles, Master Enslave + Vortex of Returning by patrolling mages did wonders.
He never stormed a single castle.