Broadly you don't want to be activating it, you would rather it was just a Grizley Bear however when things do look a bit dicey or you need something specific you are very happy with your little Bear having a slot
Or, if you're new to collecting, you can find out where to buy Pokmon cards.
Once your shambling horde reaches critical mass, boost their attack and send everyone else to the graveyard
I dont think its worth the price of admission
Cards like Yuan-Ti Malison, Midnight Pathlighter and Nadaar, Selfless Paladin are constant value engines, letting you advance down whichever of the three dungeons best suits your plans
With cards for Elementals, Elves, Faeries, Giants, Goblins, Kithkin, Merfolk and Treefolk, who are the real winners of this expansion, and who are left wanting more