Finally seeing the creatures, the terrified half-elf squeaks out a "WAAAAAUGH!". Almost autonomously, his hand slips into the component pouch again, as he takes a small (stinky) piece of bat excrement, rubs it into a ball, and combines it with a yellowish powder. Pinching the ball with his middle finger and thumb, he points at the biggest enemy that he can see, and intones a word of power.
A bright streak consumes the ball and rushes to a point right behind the Hive Lord, before a gout of flame explodes violently, enveloping all of the creatures in its wake!
Zuu takes the opportunity to relocate while the enemies' ears ring from the explosion.
Action. Cast Fireball at Level 4, centered behind the Hive Lord (the 20-foot radius hits all enemies but no allies). All foes must succeed on a DC 16 DEX save or suffer (10d6) fire damage (save halves).
Hivelord. (d20+3). Succeeds. 17 damage. 76 HP left.
Indigo. (d20+3). Fails. 35 damage. 10 HP left.
Cerulean. (d20+3). Succeeds. 17 damage. 28 HP left.
Taupe. (d20+3). Fails. 35 damage. 10 HP left.
Umber. (d20+3). Fails (should have been d20+2). 35 damage. 10 HP left.
Raisin. (d20+3). Fails. 35 damage. 10 HP left.