Should we muddy the waters even more and add ill/cold vs ill/rad? Same -regen from benumb as from lingering radiation (longer recharge though), along with also reducing an AV's heal ability, which could be pretty beneficial depending on the AV. At the levels of recharge we're talking about, cold dom would not have to worry about endurance problems like the other two, and pumps out a bunch more -res with Sleet (which you can stack more than one patch, like tar patch) and Heat Loss. Sleet also adds a fair amount of its own damage.
Not sure if the extra -res makes up for less -regen, but it's probably a contender either way.
Illusion/Cold is, like Illusion/Storm, also a good anti-AV combination... but only at the very top end. The reasons are as follows:
1: You do not have good personal defense powers.
2: You do not have +Recharge powers, thus you won't have perma-PA until the build is very mature (Lv 47+, with several purple sets). And for most of the earlier builds, the PA-gap is going to be large.
Yes, you can put out the damage, the -Resist, and some solid -Regen. But on the defensive side, they both need an expensive build to make up for the lack of +Recharge (for perma PA), or other personal defensive powers like a heal (until you get PA permanent). So it's a contender only in the "top builds" category, not in the "simple and cheap". You can probably do better with Ill/Cold than with Ill/Rad, at level 50 with an expensive build. But the difference is that I soloed my Ill/Rad to 50 going through every AV that got in the way, pre-IOs, starting with Envoy. Illusion/Cold starts a lot later, and with a lot higher price tag.
If that's the only place where you really want to fight AVs, at level 50 or near it, then both Ill/Cold and Ill/Storm work great. Storm does more damage, but has Endurance issues... Cold does less damage than Storm (but more than Rad), but also has very strong Endurance management.
I would not put Ill/Cold in the "best controller" category, though. It's a bit too specialized (good early on teams, but not so much soloing... good late against AVs but not until end game... not a great soloer at any time due to a lack of AoE... not very good AoE controls for larger teams). It's good in certain situation, but has too many gaps where it's not especially strong. Fire/Dark and Fire/Rad are good in all situations, if Ele/Poison can sap AVs then it's also good in all situations, Ill/Rad also lacks AoE damage but it's still a better generalist than Ill/Cold, etc. Ill/Cold is good, but not a contender for top Controller builds, I think, except in the specialist case of AV soloing at level 50.
