...except that that's wrong. The rules are really clear on what's one effect and what's two -- and "25 fire and cold damage" is one thing, one set of damage, and one effect--just one with two keywords.
The concept "effect" is vague. It's just some consequence of a rule or power usage - basically, just
something. Is having 2 pounds of beef equivalent to two separate pounds? Distinguishing discrete, atomic effects amongst a power's consequences is ill-defined. So, irrespective of the specifics concerning immunities, let's hope this argument doesn't hold the balance.
A target that's immune to poison is immune to all the effects of the power, as while they're fear effects, they're -also- poison effects and the target is immune to those.
Now, a real GM would probably (correctly) interpret the intent of the power that the slide is a poison effect (mabye) and that the stun is a fear effect. But lets just look at RAW interpretation, not rule-by-intent here. (a similar example is Prismatic Spray--it's easy to figure out which of the three effects are -intended- to be tied to each keyword--but one cannot do so (for the stun effect) without flavor-based interpretation)
I agree, and it's worth highlighting this notion to underline the fact that the "rules" are
not complete. Obviously, there's always rule 0 (the DM), but more subtly than that, weird corner cases or undefined rule behavior does occur and it's better to deal with it sanely than to go over rules with a fine-tooth comb when the particular corner case you're dealing with may simply have been an oversight.
Basically, it seems like the anti-immunity people in the thread are trying to treat immunity as resistance(infinity). But there's no support for that in the rules text, and you can't get there without more or less making up a rule (either immuity=infinite resistance or the [worse] "damage with multiple types is multiple effects" misrule).
The rule text is written in common-sense English. If something that resist arbitrarily strong poison, one might say it's immune to poison. If it can resist the effects of arbitrarily high temperatures, you might say it's immune to the effects of high temperature - or in a fantasy setting, immune to
fire. There's no need for the rules to state that immunity to damage is equivalent to "infinite" resistance
if that's a natural assumption to make in English. I don't think that equivalence is sufficiently obvious to make it an unwritten rule, but it's natural enough to make it unfortunate use of terminology if it
doesn't hold and isn't explicitly addressed.
CO: textev = "textual evidence".
There are no truisms -- there's only exception based design.
The game makes any number of assumptions it never describes or states. Essentially, all those bits of common sense and knowledge the players (including DM) are presumed to have are truisms - and that's a bunch.
it strikes me that a rule that is printed only once, buried in a magic item power in a splatbook, parentheses or no, is likely closer to an exception than a rule. This appears to be cooroborated by the only other non-wand magic item in the same book that deals multiple damage types: the Ring of Shadow Guard (AV, pg 159), which deals cold and necrotic damage but leaves out the "reminder text" that the Storm Shield contains.
Perhaps it's not an exception rather than a misconception however - which would suggest that the assumption isn't an odd one to make. And the opposite approach isn't clearly stated either, which makes RAI and reasonable assumptions that much more relevant - just as you say:
Not trying to be too terribly difficult here, I also believe the RAI is that you need immunity to both types otherwise you take full damage, but it's not clearly stated and I frankly think you can infer whatever you want out of the vague offerings as written.
...which is exactly what I think too: neither approach to immunities is clearly supported by the rules text which just omits this information; and it's probably best for the game to require immunities to all damage types, though it's not common enough to matter much either way.
Regardless, even if we
could conclude something from the rules, it's obviously not stated clearly and would require too much semantic trickery to have faith that the results actually represent rules by design rather than by coincidence.
