eliwood74

On the slayer skill guide under challenges, the guide says you can die before wave 31 and still have enough monsters left on your task to give it another run. However, I personally failed on that task on jad himself and checked my monsters left, and it was 9 more. On top of this, I got the task again, got to wave 5, then realized I forgot some items, so I left the cave and went back in. On wave 60 I completed my task, and did not get the bonus for killing jad. There are only about 8 extra monsters, if you leave any time after wave 5 you will not be able to get the bonus for killing jad.

I can confirm this. You must move the other globe in order to access the crate.

After the quest is completed, if you go back to Eluned (the female elf who recharges your teleport crystal) she will teach you a new enchantment. This allows your teleport crystal to teleport you right outside the temple of light where you sang in the quest to enchant the blank teleport crystal. This is helpful for slayer, as you no longer have to have a full set of mourners to get to dark beasts.