Heretic is a nice little first person shooter released in 1994, essentially a fantasy version of Doom. Though the gameplay isn't anything particularly innovative beyond what Doom had already achieved, it did add a number of magical items for the player to use. I've picked a handful of my favorites to be used for old school games, and detailed them below. I hope you enjoy!
[Note: For the interests of good gameplay, these items may be slightly modified from their original depiction in Heretic. All images from doom.fandom.com]
The Morph Ovum appears to be a large egg, crackling with green energy. When broken, 1d6 enemies within line of sight of the person who broke it must make a saving throw or turn into a chicken (HD 1 point, AC unarmored, ATK 1 bite, DMG 1 point). Creatures with 5 HD or more cannot be transformed in this manner, but instead take 1d6 damage from feathers bursting out of their skin.
The Chaos Device is a small sphere with the star of chaos inscribed upon it in lines of red energy. If the star is pressed upon, anyone touching the device is instantly transported to the safest area within 1 mile of their original position, and the Chaos Device disappears.
As a small clay pot full of dust with an ankh molded onto it, the Mystic Urn does not initially appear to be very powerful. However, when the dust is poured out onto the hand of the user, a wave of healing energy washes over them, restoring the user to their maximum possible HP as the pot crumbles to dust. This dust can even be used on the recently dead, provided they have only been deceased for 5 minutes or less.
Tome Of Power
If anyone who can practice magic opens this leather-bound book and reads even a word of its contents, they instantly and completely understand the true nature of the arcane, and are immediately a master of spell-casting (though the book immediately bursts into flames and crumbles to ash). Every spell cast within the next 1d3 minutes after reading the book work perfectly. If any saving throws are required by the target, they fail, if any dice are needed to determine the length of the effect or damage dealt, they are automatically assumed to be the maximum roll possible. However, the memory of the Tome fades fast, and after these 1d3 minutes, the power ends.