AbdulAlhazred
Legend
Pretty much the penalty to hit. I wanted a way to discourage that, but only during the alpha strike period, not during the whole fight.
That's why I proposed having the anti-control ability be a lot weaker or non-existent when the monster is bloodied, but also have anti-control work against imposed attack penalties.
The damage wasn't ridiculous. It died in two round, but I'm more annoyed that it accomplished little in round one than that it died in two rounds. It was a single solo, so it's not like it was going to last long.
How about an encounter power that the solo has which lets it shed all penalties? This won't stop the PCs from using debuffs, but it will make them think twice before heaping all their best encounter/daily ones on the creature during a round one alpha strike. Instead they'll have to mete them out more sparingly over the course of a longer fight so that the boss has to either hold its one-use shake off to deter a pile-on or use it to shake off a small penalty. Of course you will want to telegraph the existence of this power so its deterrent effect works, otherwise it will just be an 'awe crap' type thing (which might not be bad, but is probably not what you're going for).
A good way to do this would be to have a backstory that explains how some wizard put a defensive spell on the monster, or it has some item that they know will only 'dispel magic and restore vitality' once per day or something like that. The players will feel rewarded for doing their homework and you'll get a more interesting fight.
Another variation of this is the GTFO power. A boss can show up, absorb the inevitable alpha strike full of dailies, and then bail out through some ready escape mechanism, spend some plausible amount of time recovering (use up its HS, conditions wear off) and then make a return appearance, perhaps surprising the party. This is of course especially good as a lurker boss design. While in theory the boss might be able to pull this trick several times the party is likely to be wise to it the second time (you might give them some tools to defeat the tactic if they're clever, this could be a good place for an SC or just some clever use of rituals/items/things found in the environment/etc).