Wrath of Hekaton
This spirit takes the form of an old, sway-backed celestial warhorse. Marvin has Intelligence 6 and understands common.
Brockenstein has an instinctive bond with it that allows him to fight as a seamless unit. He does not need to use his “interaction with the environment” to control it in battle. While his steed is within 1 mile of you, Brockenstein can communicate with it telepathically.
While mounted on Marvin, Brockenstein can make any spell he casts that targets only himself also target Marvin.
When Marvin drops to 0 hit points, it disappears, leaving behind no physical form. Brockenstein can also dismiss Marvin at any time as an action, causing it to disappear. In either case, Brockenstein may summon the same steed if he ever casts the spell again, restored to its hit point maximum.
Formerly the mount of a famous paladin, Algorind of the Knights of Samular in Waterdeep circa 1372 DR.