Multiattack

The fellforged makes two Necrotic Slam attacks.

Necrotic Slam

Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 9 (2d6 + 2) bludgeoning damage plus 9 (2d8) necrotic damage. If the target is a creature, it must succeed on a DC 14 Constitution saving throw or its hp maximum is reduced by an amount equal to the necrotic damage taken. This reduction lasts until the target finishes a long rest. The target dies if this effect reduces its hp maximum to 0.