http://wizards.com/default.asp?x=dnd/4mspot/20080516
Some people just aren't happy unless they control the entire battlefield all the time. I know, because I'm one of those people. For those of you who share my compulsive need to dominate and control every aspect of the board, may I recommend the Immolith?
In the absence of the new Monster Manual that will presumably explain what this critter actually is, I'll attempt to explain it based on how it functions in the game. Picture a frog with a long, sticky tongue. Now picture that frog on fire. Now picture that flaming frog burning so hot that the ground around it is all melty. This glorious image is the Immolith as I understand it. I may just not read the Monster Manual when it comes out, so as to preserve this image in my head.
So, yeah, the marquee trick here is the long, sticky 'tongue' that makes every attack into "c'mere, you, and give your Uncle Meltyfrog a hug!" This would be reasonably cool all by itself, but Pale Fire makes this trick pretty darn dangerous. Consider that if I have 55 or fewer hit points, a single strike from the Immolith can almost doom me in and of itself. The initial strike does 20 (I'm at 35), activating next to the thing inflicts 15 (I'm at 20), and since you can't shift away from it thanks to Roiling Flames, there's an opportunity attack in it for you if you try to run (I'm a smoldering corpse). Of course, not running means that you'll continue to take Pale Fire damage. Your only hope is to kill the thing quickly (also a good idea because it's worth 83 points).
As for killing it quickly, the AC and DEF are working against you, but those 90 hit points are nothing to write home about, at least on a creature this pricey. Throw in Vulnerable 10 Radiant and you have a burning frog-thing that might die really fast.
So get your points' worth out of the Immolith as soon as possible. Here's one possible way to do that -- you know how Spotlight articles are always telling you to bring a meat shield for some fragile ranged attacker or support piece? The Immolith is the key to breaking this tactic. With his long Reach, he can pluck that Drow Wand Mage right out from behind his bruiser friends and lick him to death with his flame tongue.
SynergiesYou know what would be great? If there was a way to heal the Immolith. As far as I know, there isn't one yet.
Other than fantasizing about pretend creatures, I would recommend investing in beaters with better HP/cost ratios, because they'll help you kill the Immolith's victims faster and shouldn't be quite as likely to die quickly.
500-Point PlayTotally. Senor Froggy has nice attack and defense numbers, and his battlefield-control abilities are useful at any scale of play. I might even try a pair of them in a 500-point warband.