Korialstrasz, HP: 26/26
AC: 15, PPerception: 15, Spell Save: 14, Concentrating on: Flaming Sphere
Kor notices Opal pouring oil on the spiders. "Oh, that's a good idea. Just watch out for the flames". He rams the flaming sphere agains the spider swarm. Then casts a coldness spell on the giant spider.
Spoiler: OOCRam the flaming sphere against the swarm as a bonus action. Damage: (2d6)[11]