Many of the best Partner Commanders MTG succeed because their abilities naturally support scalable strategies such as card advantage, mana generation, or combat pressure
Yu-Gi-Oh Master Duel deck size: how many cards can you have in a Yu-Gi-Oh Master Duel deck
The 1999 1st Edition Shadowless Base Set Mewtwo PSA 10 population is also extremely tight at under 400
Once per turn, when an attack is declared involving a monster you control and an opponent's monster: You can activate this effect
Not that anybody will use Sage Stone or Dark Magic Curtain, like, ever, but still
(1) Special Summon 1 Sacred Beast monster from your hand or GY in Defense Position, then, if you control 2 or more Sacred Beast monsters whose original Level is 10, you can negate the effects of 1 face-up card your opponent controls, and if you do, destroy it