Tested it and it does work wonders on smaller mobs as once it hits it applys dot.

So what you do is dig down as much as possible and place a workbench, then on sides you raise ground at least 5 times. This prevents the radiation from hitting your workbench.

(downside is that once you log into a game, you will pick those items -- unless you disable auto pickup)

Let's make an oasis of death:
https://steamcommunity.com/sharedfiles/filedetails/?id=2900193949

Tagged for extinction:
https://steamcommunity.com/sharedfiles/filedetails/?id=2900194137

The more deso.... i mean Refined Eitr you have in single spot, the more sparks = faster mobs will die.

So for example in mistlands (note i havent tested it on them if they are not immune),
you can dig down 8 and raise 8 and place a workbench behind a raised wall. Then you just need to make sure that raised mud wall is as 90* as possible to prevent the mobs from jumping. Then you just place Refined Eitr into holes and they should kill those mobs for free.
Add a few raised balista towers outside your base to deal with flying ones and you should be 100% safe (just be sure you place the balista in place where you usualy dont run much as Ai
its Ai is bad).