Huge construct (Cybertronian, shapechanger), lawful good
Armor Class 21 (natural armor)
Hit Points 324 (24d12 + 133)
Speed 50 ft., (180 ft. in truck form)
Abilities Str 26 (+8), Dex 14 (+2), Con 24 (+7), Int 15 (+2), Wis 20 (+5), Cha 20 (+5)
Saving Throws Str +15, Con +14, Wis +12, Cha +12
Skills History +9, Insight +12, Perception +12
Damage Resistances cold
Damage Immunities poison
Condition Immunities frightened, poisoned
Senses darkvision 120 ft., passive Perception 22
Challenge 24 (62,000 XP)
Shapechanger. Optimus can use his bonus action to transform into a semi-truck, or back into his true form, a robot. His statistics, other than his speed, are the same in each form. Any equipment he is wearing or carrying isn’t transformed (note that his ion blaster and Energon-axe are part of him). Optimus reverts to his true form if he dies.
False Appearance (Truck Form Only). As long as Optimus doesn’t attack, cast a spell, or speak, he is indistinguishable from a normal semi-truck.
Legendary Resistance (3/Day). If Optimus fails a saving throw he can choose to succeed instead.
Trampling Charge (Truck Form Only). If Optimus moves at least 60 feet straight toward a target and then hits it with a ram attack on the same turn, the target takes an extra 16 (3d10) bludgeoning damage. If the target is a creature, it must succeed on a DC 25 Strength saving throw or be knocked prone. If the target is prone, Optimus can use his Run Over action against the same target as a bonus action.
Multiattack (Robot Form Only). Optimus makes two weapon attacks.
Energon-Axe (Robot Form Only). Melee Weapon Attack: +15 to hit, reach 10 ft., one target. Hit: 27 (3d12 + 8) radiant damage.
Ion Blaster (Robot Form Only). Ranged Weapon Attack: +9 to hit, range 100/300 ft., one target. Hit: 20 (4d8 + 2) radiant damage.
Ram (Truck Form Only). Melee Weapon Attack: +15 to hit, reach 5 ft., one target. Hit: 24 (3d10 + 8) bludgeoning damage.
Run Over (Truck Form Only). Optimus targets one prone creature within 10 feet of him. The target must succeed on a DC 17 Dexterity saving throw or take 27 (6d8) bludgeoning damage. Optimus can then move up to half his movement speed.
Leadership (Recharges after a Short or Long Rest). For 1 minute, Optimus can utter a special command or warning whenever a nonhostile creature that he can see within 30 feet of him makes an attack roll or a saving throw. The creature can add a d4 to its roll provided it can hear and understand Optimus. A creature can benefit from only one Leadership die at a time. This effect ends if Optimus is incapacitated.
Parry (Robot Form Only). Optimus adds 7 to his AC against one melee attack that would hit him. To do so, Optimus must see the attacker and be wielding a melee weapon.
Optimus can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature’s turn. Optimus regains spent legendary actions at the start of his turn.
Attack (Robot Form Only). Optimus makes one weapon attack.
Move. Optimus moves up to half his movement speed.
Transform (Costs 2 Actions). Optimus transforms into his truck form or back into his robot form.