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.
Passive Perception 15
Darkvision 60ft
Detect Evil and Good: Concentration, 30ft sphere from self, 10 min
For the duration, you sense the location of any Aberration, Celestial, Elemental, Fey, Fiend, or Undead within 30 feet of yourself. You also sense whether the Hallow spell is active there and, if so, where.
The spell is blocked by 1 foot of stone, dirt, or wood; 1 inch of metal; or a thin sheet of lead.
Calm Emotions: Concentration, 60ft range, 20ft sephere, 1 min
Each Humanoid in a 20-foot-radius Sphere centered on a point you choose within range must succeed on a Charisma saving throw or be affected by one of the following effects (choose for each creature):
Sanctuary: 1 min, 30 ft range
You ward a creature within range. Until the spell ends, any creature who targets the warded creature with an attack roll or a damaging spell must succeed on a Wisdom (DC 14) saving throw or either choose a new target or lose the attack or spell. This spell doesn’t protect the warded creature from areas of effect.
The spell ends if the warded creature makes an attack roll, casts a spell, or deals damage.
Otherworldly Slam. Melee Attack Roll: Bonus equals your spell attack modifier, reach 5 ft. Hit: 1d8 plus the spell’s level of Radiant (Celestial), Psychic (Fey), or Necrotic (Fiend) damage.
Healing Touch (Recharges after a Long Rest). One creature within 5 feet of the steed regains a number of Hit Points equal to 2d8 plus the spell’s level.
When the Drake's master falls dead, it may choose to give up its corporeal form to bring its master back to life. If it chooses to do so, the drake permanently returns to the celestial plane and will not return when summoned.
Whether or not it chooses to do so will depend upon a successful DC roll.
Drake prioritizes protecting its master, unless otherwise told to protect someone else.