Brothers in Arms

When Brothers in Arms enters the battlefield, if
you control Asterith Artorias or Argon Altora,
put a loyalty counter on each of them.
At the beginning of your upkeep, if you control
Asterith Artorias and Argon Altora, you cannot
lose the game and your opponents cannot win
the game until the end of your next end step.
Individually, they were forces few could face. Together,
they were unstoppable.