Multiattack.Withers makes two longsword attacks. He can use his Life Drain in place of one longsword attack.
Life Drain.mw 4 to hit, reach 5 ft., one creature. ({@damage 1d6 + 2) necrotic damage. The target must succeed on a 13 Constitution saving throw or its hit point maximum is reduced by an amount equal to the damage taken. This reduction lasts until the target finishes a long rest. The target dies if this effect reduces its hit point maximum to 0. A humanoid slain by this attack rises 24 hours later as a zombie under the Withers's control, unless the humanoid is restored to life or its body is destroyed. Withers can have no more than twelve zombies under its control at one time.
Longsword.mw 4 to hit, reach 5 ft., one target. ({@damage 1d8 + 2) slashing damage, or 7 (1d10 + 2) slashing damage if used with two hands.