Conjure Minor Aberration

You summon an aberration of challenge rating 2 or lower, which appears in an unoccupied space you can see within range. The aberration disappears when it drops to 0 hit points or when the spell ends.

 The freak is friendly towards you and your companions at all times. Roll initiative for the celestial, who has his own turns. He obeys any verbal commands you issue (no action required by you) as long as they do not violate his alignment. If you do not issue any commands to the aberration, it will defend itself from hostile creatures, but will not take any actions.

The GM has the freak's stats. (Example: Chuul)

At higher levels. When you cast this spell using a 9th-level spell slot, you summon an aberration with a challenge rating of 8 or lower.