mtg starter commander decks card deck These Are The Best Commander

To proliferate means to choose any number of permanents and/or players that have a counter, then give each one additional counter of each kind that permanent or player already has

You can target yourself as the player to gain 5 life

Mardu Outrider gets to lean on Arenas interface to ensure new players are ready to pay the mandatory cost, rather than have them be surprised when it enters the battlefield and demands a card as payment

cast it on Turn 3, and assuming you make your fourth land drop the next turn, you can cast Astor and have that one extra mana available

I could certainly see this Ariel being used in these sorts of decks