Boros Ascendancy

{r}{r}{w}{w}: target creature you control gains
Mentor until the end of turn.
Whenever one or more creatures attacking causes
an ability of a permanent you control to trigger,
put that many squadron counters on Boros Ascendancy.
At the beginning of your upkeep, if Boros
Ascendancy has 20 or more squadron counters
on it, you win the game.