this concept might have already been discussed but i'm gonna give it a go anyway.
Greater Conflagration (Elite) - (Nature Ritual) Create a level 1..8  Spirit. For non-Spirit creatures within its range, all physical damage is fire damage instead. This Spirit dies after 30..126  seconds.
Winter - CH1 (Nature Ritual) Create a level 1..8  Spirit. For creatures within its range, all elemental damage is cold damage instead. This Spirit dies after 30..126  seconds.
Ok. So the point im trying to make is, if one uses Greater Conflagration and then Winter, all damage (elemental and physical) will become cold damage. Now if you're a Ranger with Full frostbound armour, thats 115 Armour.
I can think of a few places where this might be very useful. Any thoughts?
EDIT: You may want to throw in one of these Mesmer stances as well for good measure.
Mantra of Frost - (Stance) For 30..78  seconds, whenever you take cold damage, the damage is reduced by 26..45 % and you gain 2 Energy.
Elemental Resistance - (Stance) For 30..78  seconds, you gain +40 Armor against elemental damage, but you lose 24..14  Armor against physical damage.