How do you kill a summoned phoenix?

Guys, tell me, I'm not very experienced, what should I use to kill this beast?! Today I was playing against a Necropolis player, and the game dragged on a bit, and then we met in an open field. First, this Necromancer summons a Phoenix, which takes down 2 of my Angels with one attack (I had 5 in total). It deals massive damage, has excellent armor, and a ton of health. Seriously, this Phoenix creates a clear imbalance in summoning magic :(. Need help...