Undead Fortitude. If damage reduces the zombie to 0 hit points, it must make a Constitution saving throw with a DC of 5 + the damage taken, unless the damage is radiant or from a critical hit. On a success, the zombie drops to 1 hit point instead. 

command. any black dragon minions under his control gain  +1 to strength 

Slam. Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 8 (2d6 + 1) bludgeoning damage.

saber. melee weapon attack: +6 to hit, reach 10 ft, one target. hit 10 (3d8 + 3) slashing damage 

burst if any ally under his control dies roll a (d20) if over 15 the monster explodes in  a 20ft by 20ft radius doing 20 damage