Which creatures from the alternative upgrade options do you choose?

Hmm... Is it necessary to remind you that magic resistance aura + magic resistance in luck is a serious chance to deflect a spell? Keep the unicorns near key stacks, and the enemy will likely not risk casting on a less important unit. If the enemy is AI, then it is worth considering that it can ignore resistance or simply knows when a spell will hit and when it won't. So, against a computer player, old unicorns are definitely not a good choice. But against a human player, it's a good thing, especially if they are forgetful and try to control a neighboring unicorn... unsuccessfully :)