Oelm
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If we're talking about a single example, Neo definitely used magic. There was a bless on the lizards. Plus, there were over 100 gnolls, so you can't consider that case as a rule. Although, the scheme is basically the same. In principle, a tier 2 or 3 creature can be captured from any castle without magic (I haven't tried it with a tower), if morale doesn't drop in the first round for the weaker units. In the last game, playing as Castle, I captured a tier 3 creature on day 121, losing a champion and about 30 pikemen, and there were 18 archers on the first day; I only built up to a citadel.
By the way, I've revised my opinion on Inferno. To capture a Utopia tier 3 creature, Marius with 60 demons is quite enough, plus a defense boost of 2. The losses are around 40 demons. If there are 80 demons, the parameters are around 8-8, then magic and offense aren't necessary. The losses are 20-30 demons.