Call to Arms is a quest in Might & Magic: Duel of Champions.
After the lingering ghost summons a wretched ghoul, the hero (Cassandra, Seeker of Light) has to level up one of their abilities, which is Might. The hero has to summon the loyal griffin, which has the cost of two resources and level two of might. The lingering ghost summons another wretched ghoul, leaving the hero to finish up the battle, by defeating the two ghouls. Note the hero has a radiant glory, a Sahaar bedouin and a lesser air elemental to win.