I've posted this as a lot of people seem to be having big
problems on the last level of the *registered* version of
Heretic - I know I did!

Here's how I finished off d'sparil on the top level of play - 
Black Plague (the one the cheat codes don't work on!). 

I'm not saying this is the ONLY or the BEST technique, just that it
worked for ME:

Save your tomes of power and invulnerability amulets. You should end
up with two of each. Save these until you've killed the dragon d'sparil
rides on and respawns - run around the 'brick fork' in the final arena
whilst killing the dragon, that way it's easier to avoid his shots.
Once the dragon is dead (and before d'sparil comes alive on his own),
save your game.

Use the tomes and amulets together and throw everything you've got
at d'sparil. Keep running around to pick up more ammo. The Hellstaff
is pretty good late on, as it fires quite a distance when NOT powered
up, so you waste less time chasing after d'sparil. Once your
amulets have worn off and your health is running low, wedge yourself
in the fork you transported in on top of, that is, position 1 or 2 
below:

     |=====
     |1
====||======
     |2
     |=====

I found that this kept the other wizards from being able to get me, they
just shoot at each other and the tops of the walls when trying to get you.
You might need a few attempts at this, drawing the wizards away BEFORE
you wedge yourself in. Once in place, d'sparil will periodically appear
in front of you. Shoot him IMMEDIATELY he appears, and keep on shooting.
Repeat this process every time he reappears. Keep saving your game, also.
Do this until d'sparil finally dies, or you've hit him enough times to
weaken him such that a final assault kills him.

Happy hunting.

Steve Phelan (UK) (100333,1615).
