Void Avatar

Void Bond. You can add your proficiency bonus to any ability check or saving throw that the beast makes.

Rend. Melee Weapon Attack: your spell attack modifier to hit, Reach 5ft., one target. Hit: 9 (1d8 + 2 + PB) slashing damage

Void Bolt. Ranged Spell Attack: your spell attack modifier to hit, Reach 120ft., one target. Hit: 9 (1d4 +  wisdom MOD + PB) necrotic damage

Sentinel Feat for the Avatar. AT LEVEL CHARACTER LEVEL 5 (( your class level in reaper no exceptions)) 

Guardian. Immediately after a creature within 5 feet of the void avatar or you takes the Disengage action or hits a target other than you with an attack, you or the void avatar can make an Opportunity Attack against that creature.

Halt. When you or the avatar hit a creature with an Opportunity Attack, the creature’s Speed becomes 0 for the rest of the current turn.