I described these are elephant sized AT-ATs. Of course, one of my players took the time to shrink themselves, get on a broom, attach a rope of climbing to the leg of the pulsepounder and proceeded to circle it in an attempt to trip it. </faceplant> I brought it on myself for describing it the way I did.
Large Construct (robot), neutral
Armour Class 18 (heavy skymetal plating)
Hit Points 315 (30d10 +150)
Speed 30 ft.
Str 24 (+7) Dex 18 (+4) Con 21 (+5)
Int 12 (+1) Wis 15 (+2) Cha 1 (-6)
Saving Throws Str +12, Con +9, Wis +7,
Skills Climb +15 (on metal surfaces), Perception +7, Sense Motive +7
Damage Resistances bludgeoning, piercing, and slashing from nonmagical weapons that aren’t adamantine.
Damage Immunities necrotic, poison, and psychic
Damage Vulnerabilities lightening
Condition Immunities charmed, frightened, paralyses, petrified, poisoned, stunned
Senses Darkvision 60 ft., passive Perception 19
Challenge 15 (13,000 XP)
Gift of the Machine God. As a creature of technology a pulsepounder robot gains many damage and condition resistances and immunities but they are also susceptible to lighting attacks.
Combat Hardened. The pulsepounder’s advanced robotic frame provides a measure of protection against attacks. The pulsepounder has a damage threshold of 10. It reduces all damage by ten.
Magnetic Step. A pulsepounder can walk upon any metallic surface with ease in zero gravity, and gains a +10 circumstance bonus on Climb checks made while scaling metal surfaces.
Multiattack. The pulsepounder robot can make three attacks – two stomps and one integrated laser cannon.
Stomp. Melee Weapon Attack: +9 to hit, reach 5 ft.; one target.
Hit: 18 (2d10 +7) bludgeoning damage.
Integrated Laser Cannon. Range Weapon Attack: +9 to hit, range 300 ft.; one target.
Hit: 25 (6d6 + 4) radiant damage. This attack’s critical range is 19 or 20.
Beam Cannon (Recharge 5-6). Rather than firing a single shot, a pulsepounder can fire a blast of energy from this cannon as an action. When it does so, it doesn’t attempt an attack roll; it simply targets a point within a maximum range of 300 feet. The robot must have line of effect to the target when it launches a blast; if the blast impacts a solid object before reaching the target area, it explodes at that point. The blast fills a 20-foot-radius spread, and all creatures caught in the blast radius take 66 (12d10) points of radiant damage (Dexterity DC 18 half).
During Combat Each robot fights to prevent entry into area C18—it pursues intruders into that area, but not out into the rest of the deck.
Morale A pulsepounder robot fights until destroyed.
Walking artillery – say no more.