This tutorial will fix a bug where the spell animation will not play if the spell kills the npc.

Server Side:

Find this in modCombat>PlayerAttackNpc

' send animation
        If n > 0 Then
            If Not overTime Then
                If SpellNum = 0 Then Call SendAnimation(mapnum, Item(GetPlayerEquipment(Attacker, weapon)).Animation, MapNpc(mapnum).NPC(mapNpcNum).x, MapNpc(mapnum).NPC(mapNpcNum).y)
            End If
        End If

and just below it place this:

  If SpellNum > 0 Then
            Call SendAnimation(mapnum, Spell(SpellNum).SpellAnim, MapNpc(mapnum).NPC(mapNpcNum).x, MapNpc(mapnum).NPC(mapNpcNum).y)
            SendMapSound Attacker, MapNpc(mapnum).NPC(mapNpcNum).x, MapNpc(mapnum).NPC(mapNpcNum).y, SoundEntity.seSpell, SpellNum
        End If