+2 yellow archon frag with casting add.
+2 blue archon frag with shield add (or anything u want).
and +1 red archon frag with str add.

The red archon frag will gave to you str enough to u have 82% or more an armor reduction. This, and the -18% reduction from corrosive projection will gave to you -100% armor reduction.
Roar will gave to you 100% or more on bonus damage. You can use also the [Chroma]'s skill from helminth.

With this build, to u recovery shield against infesteds, just use the third skill and, at follow, the second. The augment mod will do the "magic".

Have fun.