After 4 years of playing DnD with my tabletop group my wizard Therion reached level 18. So its time for him to pursue some serious wizardry goals. Smile.

• Own a permant resident.
• Ride a dragon into battle.
• Invent an own spell.

Therion: https://www.dndbeyond.com/characters/7249496/IhOtR3

Hes a Master of Conjuration Magic and the new summoning spells have been mechanically a boon to him. To include this new spells more into hits daily roleplay hes researching a way to increase the duration of these spells. 

And the result of this might be this. What you think?

Therion's extended Manifestation

You touch a spirit called by you with a summoning spell and establish a magical bond with it.

You extend the duration of the spirit manifestation to concentration, up to 24 hours. You can affect only one spirit at time and if it is ever more than 1 mile from you at the end of your turn, the spell ends and the spirit disappears. This spell allows you to maintain concentration on the summoning spell even while sleeping, casting spells as rituals or casting spells with a long casting time. If you do so, your spirit manifestation falls into an inactive, motionless state which renders it unconscious for the time.

At Higher Levels. When you cast this spell using a spell slot of a higher level, the duration increases to 10 days with a 6th-level slot, to 30 days with a 7th- level slot, to 180 days with an 8th-level slot, and to a year and a day with a 9th-level spell slot. However it still requires maintaining concentration on the summoning spell.

 https://www.dndbeyond.com/spells/1492859-therions-extended-manifestation

While I like the idea, this is a tricky spell to evaluate as basically what it's actually doing is saving you spell slots; summon aberration normally lasts up to an hour, so to have it last for twenty four hours you'd need to cast it 24 times, meaning if you can spend a spell slot to extend it you've effectively saved 22 spell slots in the extreme case.

That is very powerful, though in practice it's not likely to be anything like that; more likely you're probably only going to summon the aberration maybe five or six times in a typical adventuring day at most. The saving is also not without its own drawbacks as while you're spending fewer slots, your summon is also never being reset to its starting hit-points, so you need to keep it in fighting shape somehow during the longer duration, and it also still requires concentration so you could cast both spells, then 10 seconds later brain yourself on a low doorway and lose both spells. 😂

So yeah, it's a hard one to try and judge the balance on; I have two main thoughts:

• Does it need upscaling? My gut reaction is "no", I think 5th-level for 24 hours is plenty, and maintaining a combat summon indefinitely should require a daily cost, so there's no need for the longer durations unless you want to be able to send your summon off on a quest on its own (in which case that feels like it should be its own, specialised spell IMO).
• Should it have a limit on the level of summon it can maintain? This one I'm unsure of, as the current spell would allow a summon cast at 9th-level to be maintained, which allows you to recover the 9th-level slot the next day (so it's now saving you multiple 9th-level slots per day). My initial thought was to replace the upscaling bonus with the need to cast at the same level as the target (7th-level summon aberration requires 7th-level extended manifestation, with 5th-level still being the minimum); this would make it a lot harder, but not impossible, to maintain a higher level summon. You're still limited by concentration though so it's tough to say.

One final thing I'd say is you've published your spell too soon; you don't need to publish for private use, and it's better to post the details of your homebrew in the forum first to get feedback, then publish only once you're happy you've integrated enough feedback (and playtested it as much as possible). This way you don't end up publishing so many different versions of the same spell. Just something to keep in mind in future!

I decided to puplish it so my DM can see it and think about it.

But i also wanted to gather feedback from community and since i got no feedback from puplishing I turned to forum.

• In practice you always encounter some sort of enemies that has AoEs on his sleeve. Its not unlikely that your summon will die in the combat or a second encounter. Remember that most summons have  40-80 HP. 
• Ye I think I will discard the upcasting. It makes it too strong. Maybe making it a 6th level slot would also be fair. But anything above makes the spell not worth it. In that case its better to summon twice.

Thx for feedback so far!