Multiattack

Two Extractor Spear or Disorienting Chitter attacks.

Extractor Spear

Melee Weapon Attack: +7 to hit, 10 ft., one target, 13 (2d8+4) piercing damage + 7 (2d6) necrotic. Target's hp max is reduced by amount equal to half necrotic taken and thripper regains hp equal to that amount. Reduction lasts until target finishes short/long rest. Target dies if this reduces its hp max to 0.

Disorienting Chitter

Ranged Spell Attack: +6 to hit, 60 ft., one target, 16 (3d8+3) thunder and the target must make DC 14 Wis save or fall prone as it briefly becomes disoriented and falls.