A zombie is permanently <a href="/condition/slowed">Slowed 1</a> and can&#x27;t use reactions.

Slow

Trigger A creature attempts a melee attack against a zombie grindylow with a bludgeoning or slashing weapon
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Effect The creature must succeed at a DC 15 Reflex saving throw or become tangled in the kelp that surrounds the zombie grindylow, giving the creature a -10 circumstance penalty to its Speeds until it spends a manipulate action to remove the kelp.

Tangling Kelp

Void Healing

When a grindylow Grabs a creature larger than itself, it attaches to that creature. The grabbed creature is not immobilized, but if it moves, the grindylow moves with it.
If the creature is Medium or smaller, it takes a –5-foot status penalty to its Speeds while the grindylow is attached. The grindylow is <a href="/condition/off-guard">Off Guard</a> while it is attached to a creature.

Clinging Suckers

The grindylow moves up to 60 feet in a straight line through the water without triggering reactions. It can use this ability while grabbing a creature.

Grab

Ferocious Zombie Grindylow - amphibious, evil, mindless, undead, unholy, zombie

A zombie is permanently @UUID[Compendium.pf2e.conditionitems.Item.Slowed]{Slowed 1} and can't use reactions.

Trigger A creature attempts a melee attack against a zombie grindylow with a bludgeoning or slashing weapon
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Effect The creature must succeed at a @Check[reflex|dc:15] saving throw or become tangled in the kelp that surrounds the zombie grindylow, giving the creature a -10 circumstance penalty to its Speeds until it spends a manipulate action to remove the kelp.

@Localize[PF2E.NPC.Abilities.Glossary.NegativeHealing]

When a grindylow Grabs a creature larger than itself, it attaches to that creature. The grabbed creature is not immobilized, but if it moves, the grindylow moves with it.
If the creature is Medium or smaller, it takes a –5-foot status penalty to its Speeds while the grindylow is attached. The grindylow is @UUID[Compendium.pf2e.conditionitems.Item.Off-Guard] while it is attached to a creature.