This potion in effect gives the imbiber the ability to charm certain undead (ghosts, ghasts, ghouls, shadows, skeletons, spectres, wights, wraiths, vampires, and zombies). 

The charming ability is similar to the magic-user spell, charm person (q.v.). 

It affects a maximum of 16 hit dice of undead, rounding down any hit point additions to hit dice to the lowest die, i.e. 4 + 1 equals 4 hit dice. 

The undead are entitled to saving throws versus magic only if they have intelligence. Saving throws are made at -2 due to the power of the potion, but the effects wear off in from 5-20 rounds. 

To determine type of undead affected by a particular potion, roll d10 and consult the following table:

1 Ghasts

2 Ghosts

3 Ghouls

4 Shadows

5 Skeletons

6 Spectres

7 Wights

8 Wraiths

9 Vampires

0 Zombies