On initiative count 20 (losing initiative ties), Zargon can take one of the following lair actions; it can’t take the same lair action two rounds in a row:
Dissolution. Zargon dissolves into a glob of slime, seeps to an unoccupied space anywhere in the lair without provoking
opportunity attacks, then re-forms.
Spell Breaker. Zargon targets up to two creatures it can see within the lair. All spells of 5th level or lower affecting the targets end.
Sucking Slime. Zargon creates a 20-foot-radius puddle of slime on the ground centered on a point within the lair. The slime is
difficult terrain, and each creature in that area when the slime appears has the
grappled condition (escape DC 15). Aberrations and Oozes are unaffected by the slime. The slime lasts until Zargon dies or until it uses this lair action again.