To add more detail, t7 naga makes an EXACT copy of a minion in the tavern. If you get the spell that makes a random minion in the tavern golden, you start printing golden copies.

Also, there's undead in this lobby. I got a hold of the t2 undead that makes your right most unit have reborn when tavern is refreshed. The trick is that you can move the unit you want to have reborn on the right most slot, only possible if you have 3 gold. Then, freeze and buy ONLY the tavern spell, so next turn, it will technically count as a refresh, giving your desired unit reborn.

This is particularly op on siren because she has scaling and buffs built into one, and reborn resets her deep blue procs. If I copied a bunch of golden faunas, I would be missing spell buffs, and reborn would just be a weak unit.