I don't regret allowing the party Bard to take Find Greater Steed as a Magical Secret, but I am starting to realize it may be a perennial source of questions.
In our last session, the Bard summoned her steed:
While mounted on it, you can make any spell you cast that targets only you also target the mount.
While mounted, she used her Hat of Disguise to cast the Disguise Self spell,
While wearing this hat, you can use an action to cast the disguise self spell from it at will.
targeting only herself and thus creating an independent cast of the spell on the mount. While the original spell has a duration of 1 Hour, since it was cast from the Hat it is also subject to
The spell ends if the hat is removed.
The spell on the Bard will certainly end if the hat is removed – but will the replicated and independent spell targeting the mount also end when the Hat is removed from the bard?
Best Answer
The spell is only cast once, so when it ends, it ends for both the bard and the mount.
Nothing in the description of find greater steed indicates that disguise self is cast more than once:
It only makes the steed an additional target of the single spell you cast; it is not a “replicated and independent spell targeting the mount”. You cast one spell, and that one spell targets yourself and your steed. Then, disguise self says:
So when the spell ends, the disguise effect ends. Since the spell ends when you remove the hat, the effect ends on both the bard and the steed at that moment.