[4e] - Stacking Resistance, Variable Resistance, and Resist All

[Shadow_Elf]

Okay, so, it came up at some point in some session, or maybe while homebrewing, that nowhere does it say in any official material whether resistances stack. If my Stormsoul Genasi wears a Stormwalker's Cloak, I think it should stack. If my Adamantine Soldier wears Tarrasque-Plate Armor, I think that should stack.
The only reference to stacking resistances in any Wizards material is the Variable Resistance entry in the appendix of the Monster Manual, which says that variable resistance does not stack with a monster's base resistances.

So, any ideas?

[Starsinger]

By default they don't stack. The items do not improve your resistances, they grant you resistances.

[Shadow_Elf]

By default they don't stack. The items do not improve your resistances, they grant you resistances.

Is that just supposed to be understood in the wording, or does it have a rule about that somewhere? Since Tarrasque Plate Armor makes so much sense for an Adamantine Soldier, yet it is made obsolete by the Adamantine Soldier's Level 24 feature. If there wording in there that means they would stack? The fluff of the feature seems to imply that your armor is improved by virtue of you wearing it.

[Yakk]

By default, they don't stack.

However, I'd personally allow two kinds of resistances from two kinds of sources (item vs class feature vs power vs racial ability) to stack at least to a limited degree.

A simple system that is resistant to abuse is you gain the full benefit of the highest source of resistance, then half the benefit of the next source of resistance, then 1/4 the benefit of the next source of resistance, etc.

Then someone with a 10 resist cloak, 7 racial resist, and a class power that grants 5 resist, would end up with 15 total (10 + 3=(7/2 round down) + 1=(5/4 round down) resist.

Given an infinite source of resist 10 effects, this generates 10+5+2+1 = 18 resist. In general, you can at best double the "top strength" resist, assuming an infinite set of additional sources of resist.