This is somewhat slower with the change to EoE, but a A/R using Barrage and EoE can wipe up the Gargs very quickly if you get them aggro'd correctly. (Bleeding from crit strike to get health below EoE cutoff)
I used my R/x before the EoE nerf and farmed lots and lots of skulls. Can still do R/x by barraging one group once then barraging another to death to kill both groups.
I tried bringing my 135hp monk with SoJ to The Great Northern Wall mission but the giant wave of charr at the end kept attacking and running away before I eventually died because I shoved everything into mending and watchful spirit, but quantity won and they all slapped me to death. My 2 searing flames heros were also too stupid and got thrashed. anyone know of a way to take em on?
I soloed them pre-update in an Ether Renewal build.
I don't know how fast it would be now, but classic geomancing should keep the damage rate at 0. Even if there's degen, which I don't recall one way or the other, as long as there aren't other problems too one can power through that.