I have been looking at playing a conjuration wizard, but annoyingly the only spells that I am interested in are Unseen Servant and Tenser's Floating Disk neither of which have any real use beyond RP (i.e. no combat effectiveness).
I have been looking at homebrew spells to try and propose to my DM. For ease, I would like one scaling spell that covers enough bases, but doesn't get overpowered. The character would likely start at level 1 and possibly go all the way to level 20, so this spell needs to be balanced for the entire level range. It would be selected in the same way as any other 1st-level spell (creation, level up, found as a scroll, etc.).
The spell below is my attempt:
SeriousBri's Magnificent Summoning
Casting Time: 1 Action
Range: 90 feet
Components: V, S, M (something irrelevant)
Duration: Concentration, up to 1 minute
You call forth a creature or group of creatures to serve you. The caster chooses a single type of aberration, monstrosity, or ooze with a CR of 1/4 or greater that you have either seen before or researched to become aware of, and can summon a number of them with a combined CR of 1 or lower. The summoned creatures appear at a point on the ground within range, and disappear when reduced to 0 hit points or when the spell ends.
The creatures are friendly to you and your companions for the duration. Roll initiative for all the creatures at once and they share a single turn. The creatures obey any verbal commands that you issue to them (no action required by you), and each creature can be issued a unique command. If you don't issue any commands to the creatures, they defend themselves from hostile creatures but otherwise take no actions.
At Higher Levels: When you cast this spell using a spell slot of 2nd level or higher, the combined challenge rating of the creatures you can summon increases by 1 for each slot level above 1st.
Other than possibly summoning a set of niche creatures (which I would avoid), how balanced is this spell?
A point of clarification is that I intend for the spell to allow summoning groups of creatures, but only when they are all the same - so I could summon 2 gibbering mouthers, but not a gibbering mouther and a black pudding together.