Summon Celestial (upcasted to 6th level) for the 6th level Mystic Arcanum

I noticed that there are not any feasible summoning options for a good warlock for the 6th level Mystic Arcanum.

Warlocks can pick Summon Undead and Summon Fiend which are, let's say, of questionable ethics.

I hate how evil coded is Warlock by default. It seems a remnant of previous editions flavor. 

I know that if you pick Celestial as subclass you obtain Summon Celestial with the 5th level spells, but not all good warlocks might want to pick that subclass, there are also Vestiges warlocks and Genie (Djinn) Warlocks for instance which are a great fit for a good character. 

How bad would it be for a DM to allow a good Warlock to pick Summon Celestial (upcasted to 6th level) for the Mystic Arcanum instead of Summon Fiend?

Would it be balanced/ reasonable?

Not allowed by the official rules since the spell isn't on the Warlock list, but as a house rule it's probably fine. The Mystic Arcanum rules mean you only get one of those per day, which puts a pretty hard limit on how much abuse is possible with any spell.

Quote from wagnarokkr >>

Not allowed by the official rules since the spell isn't on the Warlock list, but as a house rule it's probably fine. The Mystic Arcanum rules mean you only get one of those per day, which puts a pretty hard limit on how much abuse is possible with any spell.

 It seems that a level 6 Summon Celestial would be equivalent to the regular Summon Fiend right? In term of power.

Quote from Jayce_Danathar >>

Quote from wagnarokkr >>

Not allowed by the official rules since the spell isn't on the Warlock list, but as a house rule it's probably fine. The Mystic Arcanum rules mean you only get one of those per day, which puts a pretty hard limit on how much abuse is possible with any spell.

 It seems that a level 6 Summon Celestial would be equivalent to the regular Summon Fiend right? In term of power.

Yeah, I think that's a fair assessment.

Quote from wagnarokkr >>

Quote from Jayce_Danathar >>

Quote from wagnarokkr >>

Not allowed by the official rules since the spell isn't on the Warlock list, but as a house rule it's probably fine. The Mystic Arcanum rules mean you only get one of those per day, which puts a pretty hard limit on how much abuse is possible with any spell.

 It seems that a level 6 Summon Celestial would be equivalent to the regular Summon Fiend right? In term of power.

Yeah, I think that's a fair assessment.

 I would say this substitution would be just fine. The two spells are very similar, with only minor mechanical differences that invoke the flavor of fiend vs celestial. I would allow this substitution as a DM for non-evil Warlocks looking for a Summon spell.

Quote from Jayce_Danathar >>

I noticed that there are not any feasible summoning options for a good warlock for the 6th level Mystic Arcanum.

Warlocks can pick Summon Undead and Summon Fiend which are, let's say, of questionable ethics.

I hate how evil coded is Warlock by default. It seems a remnant of previous editions flavor. 

I know that if you pick Celestial as subclass you obtain Summon Celestial with the 5th level spells, but not all good warlocks might want to pick that subclass, there are also Vestiges warlocks and Genie (Djinn) Warlocks for instance which are a great fit for a good character. 

How bad would it be for a DM to allow a good Warlock to pick Summon Celestial (upcasted to 6th level) for the Mystic Arcanum instead of Summon Fiend?

Would it be balanced/ reasonable?

 Reminder that Vestige can empower their vestige at 14 to make it a summon celestial.

Quote from HawkwinTenebrae >>

Quote from Jayce_Danathar >>

I noticed that there are not any feasible summoning options for a good warlock for the 6th level Mystic Arcanum.

Warlocks can pick Summon Undead and Summon Fiend which are, let's say, of questionable ethics.

I hate how evil coded is Warlock by default. It seems a remnant of previous editions flavor. 

I know that if you pick Celestial as subclass you obtain Summon Celestial with the 5th level spells, but not all good warlocks might want to pick that subclass, there are also Vestiges warlocks and Genie (Djinn) Warlocks for instance which are a great fit for a good character. 

How bad would it be for a DM to allow a good Warlock to pick Summon Celestial (upcasted to 6th level) for the Mystic Arcanum instead of Summon Fiend?

Would it be balanced/ reasonable?

 Reminder that Vestige can empower their vestige at 14 to make it a summon celestial.

 Sure, but I would let even the other subclasses (like an Archfey or Great Old One) substitute their Mystic Arcanum like this if they didn't want an "evil" summon.