The spell you tried didn’t really work out the way you wanted.
Walk to the right and look at the grave of Michael Gower again. The zombie is gone and the grave is empty. Look in your inventory and look at the spellbook. So there is a way to set thing straight again. Walk back to the left into the streets of Reality and on the left is Bill Cosby lying dead on the ground. Search the man to find his WALLET.
Enter the Yahtzeebrand General Store and talk to the shopkeeper. Ask if he has seen the zombie. Take the POOP SCOOPER from the shelf in the middle. You pay with the stolen wallet. Take the bottle with WATER from the left on the top shelf and pay for that as well. Leave the shop on the south and use the poop scooper on Bill Cosby to take some of his HUMAN GORE. Walk to the left into the alley. Talk to the bum and ask about the zombie. He has seen him going into the house. Now you need to get in there.
Use the wallet on the jukebox to let change the song and let the bum salute. Use the bum to climb through the window into the house. Look at the spellbook in your inventory to find the invisibilty spell and use the spell on yourself to become invisible. Only your spectacles are visible. Then use the door in front of you to enter the house.
On the table with Punk Alan is a bottle of Smirnoff Wodka. Use the bottle of water from your inventory on the bottle of WODKA to swap them. Alan might not survive but who cares. Walk to the south to leave Scid’s bar. Walk to the right to the graveyard.
Use the human gore on the grave and use the bottle of wodka on the pentagram. Use the fire spell from the inventory to turn the zombie into a corpse.
Game source: A copy of the game was found here on the internet.