Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
Alexios, Deimos of Kosmos attacks each combat if able, can't be sacrificed, and can't attack its owner.
At the beginning of each player's upkeep, that player gains control of Alexios, untaps it, and puts a +1/+1 counter on it. It gains haste (This creature can attack, and as soon as it comes under your control.) until end of turn.