Activate the following cheats by entering the corresponding codes:

CHEAT FUNCTION - CHEAT CODE
Changes map mode - ravmap (at map screen)
F1 creates screenshot - ravpic (at title screen)
Invincibility - quicken
All weapons, ammo - rambo
All skeleton keys - ravskel
Walk through walls - kitty
Level select - engage
Deathmatch level - engage41
Full health - ponce
Toggle power-up mode - shazam
Kill all monsters in level - massacre
Chicken mode - cockadooledoo
Sixteen of each inventory item in the game NOTE 1 - gimmez0
Ring of Invulnerability - gimmea
Shadowsphere - gimmeb
Quartz Flask - gimmec
Mystic Urn - gimmed
Tome of Power - gimmee
Torch - gimmef
Time Bomb of the Ancients - gimmeg
Morph Ovum - gimmeh
Wings of Wrath - gimmei
Chaos device - gimmej
Sound debug - noise
Ticks-per-frame counter - ticker
Instant death - iddqd
No weapons, ammo - idkfa

NOTE 1: Items will reduce to one of each instance after level completion. Wings of Wrath cannot be carried over to next level.

At the Cathedral (level 6), flip the end switch. Do not complete the level. Instead, go back up the green key stairs and turn right. Go down the hall until you see an opening in the wall that was not there before. Enter it, kill the enemies, and flip the switch to open another door down there. Go on the right "end" teleport to complete the level and travel to the Grave Yard.

When having low health (1-10), there is an easy way to to boost your health by about 30. The lower the health, the better. Pull out the Phoenix Rod and walk near a wall. Blast the wall, and if you are at low enough health and did the trick correctly, your health will go up.