Steps in each phase play out as normal
Thanks to its Affinity ability and colorless nature, its very easy to make this card come out without spending a single mana
For example, Gaea's Cradlethe most valuable gold-bordered cardshows up in only one deck: Matt Lindes Mono-Green Stompy list from 1999
They just so happen to also be creatures that can attack
The only certainty produced from these conversations came when I asked, "How bad would it be if they entered on your side, then moved to the protector's side during combat?" Finally, everyone agreed on something: it would be very confusing and distracting, would potentially shift around planeswalkers you were planning to attack, and I shouldn't have suggested such a thing
Definitely Mythic Rare, and a great card in the tradition of Kongming, "Sleeping Dragon" (2WW 2/2 Other creatures you control get +1/+1)