Atla Palani, Nest Tender looks hilarious. I do slightly wish that the cheat-into-play ability were tied to the tokens themselves and not Atla (so they would still be useful if Atla leaves), but being able to function as an Egg tribal commander is better design overall. Also works with changelings, I suppose -
Mirror Entity is particularly interesting.
Assuming you have a +1/+1 counter on the Entity and Atla, you could activate Entity for 0 as many times as you want to chain through the creatures in your deck. Throw in some token producers and an Eldrazi Titan (such as
Kozilek, Butcher of Truth) to shuffle things back in, and you can cheat out every creature in your deck, which seems perfectly fair and reasonable.
....awkwardly, I sort of want to test Atla in my tap-ability-tribal deck, which is full of tiny creatures that aren't really worth cheating out. Still, quantity has a quality all its own.