Notes: The following rules were prompted by a desire to build custom undead and have a reasonable way to determine their Turn number, and then by a desire for “turn/control” rules for other kinds of creatures (elementals, demons, nightmares, fey).
Since the 1d20 probabilities mapped very closely to a 1d6, and I prefer small dice and numbers when I can get away with them, I mapped them to 1d6.
Shamblers are re-skinned zombies for my setting; wraiths are custom undead of the incredibly nasty and incorporeal sort.
Some creatures can be turned, causing them to flee for ten rounds by the most effective and fastest means available; those that cannot flee, cower (unable to take actions, and suffering a –2 penalty to AC). If the character who turned the creature attacks it in melee combat (missiles and spells do not count), the turning effect is broken.
Creatures that can be turned have a Turn number equal to 3+, increased by +1 per HD up to 6 (round down), by +1 per two HD above 6 (round down), and by +1 per two special * abilities (round up).
A character who can turn creatures of the appropriate type must roll 1d6 + level and get a result equal to or above the Turn number. On a success, this turns 2d6 HD of creatures. On a success by at least 3 (i.e., rolling an 8 or higher against Turn 5+), the creatures are destroyed, banished, or similarly removed from play. Regardless of the 2d6 dice roll, at least one creature will always be turned on a success.
Once a turning roll is failed, no further turning rolls may be attempted during this encounter; otherwise, a character may turn creatures as often as desired.Example Allan is a third-level cleric facing a crowd of 10 shamblers (undead, HD 2*, Turn 6+). He rolls 1d6+3 to turn undead and gets a 7, and turns 10 HD—five of the undead flee before his religious fervor!
On the following round, he rolls again, and gets a 9! He destroys 8 HD of corpses—four of them collapse lifelessly, leaving only one facing him.
Unfortunately, his third roll is a 5, and the last is not turned . . . and he can no longer continue attempting to turn undead this encounter.
Later, as a tenth-level cleric, he faces two wraiths (undead, HD 8******, Turn 13+). He rolls 1d6+10 and gets a 13 exactly, then rolls 5 HD. Since the wraiths have 8 HD, the minimum of one wraith is turned, and he can try again next round.
Righteous Turning. The righteous turning proficiency grants a +1 on the turning roll, and adds the character’s WIS bonus (minimum +1) to the HD turned.
Control. Some classes can control turnable creatures instead. This works just like turning, above, but results in control of that many HD for one turn per level; on a destroyed result, control lasts for one day per level.
Diabolical Control. The diabolical control proficiency grants a +1 on a controlling roll, and adds the character’s WIS bonus (minimum +1) to the HD controlled.
Converting Back to 1d20
Turn number starts equal to 7+, increased by +3 per HD up to 6, +3 per two HD above 6, and +3 per two special abilities (round up). Clerics roll 1d20 + (level x 3). Righteous Turning has its old effect back.
Note that to get results identical to the books, you have to adjust the HD asterisks to match the number of actual special abilities (for example, in the core book, a zombie gets one * for undead immunities, while a mummy gets the same single * for those undead immunities, pants-wetting fear aura, and one of the most powerful curses in the game; these rules assume the mummy has *** instead).