Typically, theyd end up out-of-position, and it wouldnt be the Ajani Vengeant that killed them but the Purphoros, God of the Forge or Blood Moon that they opened themselves up to because they fought Ajani
Each time you proliferate, youll be further reducing the size of your enemy creatures that have -1/-1 counters on them
If all of them are heads, this attack does 120 more damage
Each of these decks has a distinctly different power level, which means no matter the power level of decks at a random table of players, I have something that wont be over or under powered for the game people want to play
For a card to become a sideboard staple, it either needs to be the single most efficient version of an effect (Natures Claim), have a particularly backbreaking impact on the targeted deck (Stony Silence), or be so broad as to have an impact in multiple matchups (Rakdos Charm)