Bad example.
The rules for immunity in the PHB3 specifically tell you that immunity to poison specifically makes you immune to non-damaging parts of the power.
If you get hit with a power with the Fear and Poison keywords:
If you are immune to fear, you take damage, but nothing else happens
If you are immune to poison, you do not take any poison damage, no non-damaging parts of the power apply, but you'd take any non-poison damage the power has
If you are immune to fear AND poison, it works exactly as if you were only immune to poison.
Prismatic Ray, for instance, would still deal its fire damage.
The only keyword you can be immune to and avoid -everything- is gaze.
Doesn't happen often.
immune: If you are immune to a damage type (such as cold or fire). you don't take that type of damage. lf you are immune to a condition or another effect (such as the dazed condition or forced movement you are unaffected by it. If you are immune to charm, fear, illusion, poison, or sleep, you are unaffected by the nondamaging effects of a power that has that keyword. Immunity to one part of a power does not make you immune to other parts of the power. For example, if you are immune to thunder, a power can deal no thunder damage to you, but the power could push you.
AV, pg 121 - Storm Shield daily power:
"Power (Daily ✦ Lightning, Thunder): Immediate Reaction.
Use this power when you are hit by a melee attack.
Deal 2d6 lightning and thunder damage to the attacker.
(The attacker must have resistance or immunity to both
damage types to reduce or ignore this damage.)"
Since it's written in parenthesis I believe it's reminder text, which should indicate a general rule and not a specific exception.
Actually, deliberately crafted example (on my part), but yeah.Bad example.
The rules for immunity in the PHB3 specifically tell you that immunity to poison specifically makes you immune to non-damaging parts of the power.
If you get hit with a power with the Fear and Poison keywords:
...
Nope. I've looked around for immunty to see how hosed some types are (who can pierce resistance, but would be hosed by immunity to their damage types), and they're -really- rare.Also, realistically, how often does immunity to a damage type happen that you'd EVER need to adjudicate this rule? ARE there monsters common enough immune to any damage type other than Poison?
Damage IS an "effect"
In this reading (using the fire/cold example) it can be clearly read as "Resistance or immunity to (fire) does not protect a target from the power's other (damage types or non-damaging effects)." This reading supports my position because the power also does cold damage and immunity fire does not protect you from other (damage types or non-damaging effects) so you clearly take full damage.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.