Are -dmg modifiers applied to barrier?

[Stand The Wall.6987]

If not, should they be?

[Stand The Wall.6987]

Also wondering if poison affects barrier.

[rng.1024]

Barrier simply temporarily increases your vitality, so no they don't get affected by your dmg modifiers (vitality isn't a factor in those) - it only absorb some of the damage that comes through after the calculations are done.

Since barrier isn't healing (green numbers) but rather a transform-like upscale of vitality, there is nothing to suggest poison affect it in the least. If it does, I'd imagine barriers would get 33% less of a bonus from your healing power, but it already scales so low it's not going to make a notable difference unless you run minstrel/magi.