Cynicade
Skeletron Prime
Hallow doesn't eat jungle, IIRC. Hallow solution might be a good thing to stop the corruption/crimson if your jungle's at threat, as hallow can't be converted (unless you use different solution)
Only included Hallow because it wouldn't surprise me if it suddenly became ravenous if we did make the jungle immune to Corruption and Crimson conversion.
I've seen stupider things happen.