Multiattack

Two Greatclub or Runic Blast attacks.

Greatclub

Melee Weapon Attack: +10 to hit, 15 ft., one target, 19 (3d8+6) bludgeoning damage + 9 (2d8) fire.

Runic Blast

Ranged Spell Attack: +7 to hit, 60 ft., one target, 25 (4d10+3) force and target's speed halved until end of its next turn (DC 16 Con not half speed). Fiends have disadvantage on the save.

Invisibility Rune

Magically turns invisible until it attacks or until its concentration ends (as if concentrating on a spell). Any equipment the giant wears or carries is invisible with it.