Ultralisk

The ultralisk is a zerg heavy ground unit. Kerrigan can summon an Ultralisk and Ultralisks can be spawned on the Braxis Holdout, and are part of the zerg waves that are sent against opponents. Additionally, an ultralisk skin called Butcherlisk is available for The Butcher.

Background
Bearing little resemblance to the docile Brontoliths from which they were evolved, Ultralisks are the most powerful of the Zerg ground forces. They serve as the backbone of the Swarm’s armies and are as dangerous as any armored vehicle. These massive monstrosities are used as living battering rams against their enemies. Their large bone-like scythes allow them to tear through most known substances with ease. The Ultralisk’s genetic material has been subjected to countless tests and experiments, and only the final viable code is used by Zerg Larvae to morph into new Ultralisks.

As a Summon
An Ultralisk is a Summon created by Kerrigan after learning her Heroic ability Summon Ultralisk. The Ultralisk attacks a target and its attacks splash to nearby enemies for 50% damage. Can reactivate the Ability to retarget the Ultralisk. Lasts for 20 seconds.

Summoning Ultralisk while Kerrigan is affected by Spell Power buff/debuff, increases/decreases Ultralisk's Basic Attack damage. Gaining or losing Ability Power after Ultralisk is summoned does not affect it.

As a Monster
Ultralisks are monsters unique to the Braxis Holdout battleground and are part of the zerg wave. Periodically, two beacons and one pen from each lane (belonging to opposite teams) will activate. When both beacons are held by the same team, that team's pen will begin to fill with Zerg. You always have 1 Ultralisk to start with. 75% spawns a new Ultralisk (2 maximum). When one team's pen is full, the Zerg are released to attack down their respective lanes.