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I had 190 Troglodytes from the start, 3 stacks, and 2 native heroes, and in order to take the maximum Griffon Conservatory without a gr. stack on 111, you need to spawn in the Dungeon, buy a spell book with a buff, something to make the spell duration last about 3 rounds. That's all.
I took it with 200 Troglodytes on 115, losing about 70.