This is the build I use for armor farming on infested, I run it on non-MM starting from wave 21. If you need more time to upgrade then start wave 20. I do not reccommend running mixmode since it is significantly slower but this build will work for that if you want to do it.

The listed stats are MY STATS, I haven't tested it with lower but I would assume it is possible. If you struggle then I would suggest using a 3rd boost summoner or adding minions as needed.

Hint 1: With my 5k range monk I use a buff beam here but do not upgrade it, if you have smaller auras you might wan't to upgrade it a few times. Just make sure that it's as big as possible while not overlapping the spawn to the right of it (this will tank its HP very quickly). With 8k range I don't use a buff and instead make the physical beam at hint 4 5DU instead of 3DU.

Hint 2: 5 DST's pointed in the directions of the arrows, put a boost summoner here with a Huntress and Apprentice guardian.

Hint 3: 9 LT's boosted with a Huntress and Monk guardian

Hint 4: If you have a 3DU physical beam here it will get low on hp during waves 30-35, a flash heal may be required during these later waves.

This build is based on Washboard's build. Go check his out if you don't like mine.