ToME: the Tales of Maj'Eyal

Hello!

I saw a video on youtube.
There was someone fighting the end fight at lvl 49.
The trick was to get a lvl up killing the first boss.

Now I will start the last 10 lvls (it is ten right?) to try for the last fight.
I play a halfling rogue, and this is night mare mode.

Last time I was here I went for the fighter which was a bad mistake.
Now I will try again (if I survive the ten lvls) attacking the wizard opponent first instead.

My question is: How many % does the wizard give if I manage to kill him)?
IE How far into lvl49 is it wise to go before entering the last lvl?

In normal I think you can get level 46 => level 50 by killing Elandar.