Life Bond. When you regain Hit Points from a level 1+ spell, the steed regains the same number of Hit Points if you're within 5 feet of it.
Otherworldly Slam. Melee Attack Roll: Bonus equals your spell attack modifier, reach 5 ft. Hit:1d8 + summonSpellLevel of Radiant (Celestial), Psychic (Fey), or Necrotic (Fiend) damage.
Fell Glare (Fiend Only; Recharges after a Long Rest). Wisdom Saving Throw: DC equals your spell save DC, one creature within 60 feet the steed can see. Failure: The target has the Frightened condition until the end of your next turn.
Fey Step (Fey Only; Recharges after a Long Rest). The steed teleports, along with its rider, to an unoccupied space of your choice up to 60 feet away from itself.
Healing Touch (Celestial Only; Recharges after a Long Rest). One creature within 5 feet of the steed regains a number of Hit Points equal to 2d8 + summonSpellLevel.