Its body melds to projectile which gets lodged into it, absorbing the item into its body removing any possible weak spots or hand holds.

claws: hit +4, dmg 2d6 +3

roll: 25ft long 20ft wide square in any direction. Dex save dc14, dmg 1d12 +2. Abberant moves to the end of the range.

Lightning blast: 50ft long 5 foot wide beam of lightening. hit +3, dmg 2d10 +2  

multiattack: hit +3, 3 attacks DMG 1d10 +2

Cast a silence aura in a 25 ft radius sphere which follows itself.

Magic culling: Absorb magic from a fainted enemy removing thier spell slots, adding a failed death throw, and healing for 2x the level of each spell they absorb. 

Leap: 30ft jump which knock enemies prone in a 20ft radius from the impact.

rage: gains all melee DMG resistance and adds +1 to all attack rolls until it is either not dmged or doesn't do DMG during one round. (Can't be raging during arcane exspulsion)

reaction attack, use claws.

Hellish rubuke, dex saving throw DC 14 if successful take half dmg 3d10 

If the abjurant has absorbed a combined amount of 25 spell levels, it can do one of 2 things.

Magic revivification) On death it can imbue its magic into a party of its body and rematerialize itself, at full health with 0 absorbed levels, at the location of the part they imbued it into. But if this peice is magically erased, contained, or siphoned  the abjurant will be destroyed in the process. 

Arcane exspulsion) upon reaching below 25 hp the abjurant can become a magic incarnate sacrificing all its actions for the next 3 turns to begin a magic based explosion. It becomes immune to all magic DMG, healing for half the DMG done. It takes half DMG from all physical DMG, and can use one of its 2 reactions to lash out at an attacker for a dex saving throw DC12 to do 1D8 lightening DMG. If the beast is not killed or subdued before 3 turns are over it will unleash all its started magic dealing 1d20 DMG per 5 spell levels it had saved in a 100 ft radius.