Also, I just would like to help y'all understand, but Implosion will be better.
It can kill any monsters in DDO including undeads and construct (except wind ele).
But, it's not the only reason why it's better. Using necro instant kill spells as divine
will cost really a lot of spell points if you compare to implosion (5kills max).
For example: let's say you have best necro Dc in game (cleric) you would need 250sp
to kill 5 mobs. Now, implosion can kill 5 mobs with just 50sp