Question about horror marks

[Edi]

Vicious Love said:
We know horror marks come in varying degrees of severity(The one inflicted by the spell has a nearly negligible chance of spontaneously summoning a horror, even if you spend a few dozen turns forging and casting in a magic-3 province), but we also know various items(The Tartarian Chains, for instance) have a chance of summoning horrors or similar nasties independently of any marks.
We've reason to consider both possibilities, but it'd take plenty of experimentation to ratify either one.
Little help?

Tartarian chains do not confer a horror mark, they just give an x% chance of an assassination attempt by an Ashen Angel every turn, where x is relatively small.

The Forbidden Light on the other hand confers possibly the worst horror mark ever, I've never seen a bearer go more than five turns before being splattered all over the place. The Sceptre of Corruption also gives a more powerful horror mark, if my understanding is correct. By the way, both of these are cursed items, you can't remove them once equipped. You can always reforge after they are lost, however.

And it seems like horror marks from several sources would (at least partially) stack. Having a mage horror marked by the spell, then putting Magebane, Sceptre of Coruption, Robe of the Magi, Gift of Kurgi and The Forbidden Light on one would probably give some very interesting results...

Edi