One of the many cool things about Stilt man is that you can get in a one-two punch colossal retaliation if you have him go 2nd. In other words, Have Atom retaliate 1rst and then Stilty can follow up because he doesn't have the same wording as the colossals from SM/WW do

My buddy wanted to play his shiny new Spider-Man Family figs in a 1000-point game recently, so naturally I made a Sinister Syndicate team to face them. Stilt-Man here had four extensions. Also, like the rest of the team, he had the Original Sinister Six ATA. After a Colossal Retaliation and a Quake, he became a contender for MVP, rivaled closely by Overdrive's incredible taxi-ing and OP kit Venom's simultaneous damage output and Defend. Dishing the ATA's tokens to half of his team on my second turn crippled him. I didn't think ahead about how brutal he would be with the ATA, but man, he was. He even lived to tell the tale thanks to his leg extensions.

Played a 600 point game vs. my friend. I ran Sinister Syndicate [FF Kingpin, SFOSM Speed Demon, Stiltman, Beetle, Sandman, Overdrive, Electro, and LE Rhino and the Original Sinister Six ATA. Fought X-men from the new set [Cyclops, Wolverine, Sprite, Sunfire, X-23, Symbiote Object, Proteus Equip etc]. Using Kingpin, Speed Demon, and Stiltman together allowed Stilty to retaliate with an 11 to hit and prob his quake. Stilt man survived an initial pulse wave from Sunfire [3 damage] to end on his last click before he did anything that game except for move. For the rest of the game, his trait allowed him to avoid all the other attacks against him and retaliate every turn. Stiltman MVP and will be on all my Sinister teams from now on :D

Is he a unique? The picture on the card has silver behind it, but I don't remember the dial having a silver ring.

Background color is rarity in the new card format. The ring around the portrait will determine unique/prime, now. In this case, Stilt-man is a common (even if the background is kind of silvery white), and the Rares have a much more pronounced silver color.

So is he just a regular character when he has exactly 3 leg extensions? He's giant when he has 2, and colossal when he has 4 or more?

Damn. Never noticed that. I checked an actual card and the "at least" 2 is definitely missing. Poorly worded...

How was the Beyonder ruled again? He had a similar issue with Multiattack.

He is still considered 'giant' with three leg extensions. See Rules Recap #24 in the links above for WK ruling.

I actually think this piece is bonkers good at 65 points. Just hang back and teleport in using Retaliation, then after smacking the target (with knockback from Force Blast) you can pile a Quake on top of it to affect whomever is around. The hard part of Quake is usually positioning... but it's not a problem here since you can situate him anywhere in a 3-square radius around the aggressor. In fact, sometimes it pays to place adjacent to someone who did NOT trigger your Retaliation: he could use his free attack with Giant Reach:3 to smack the original aggressor even when adjacent to someone else, and then after that jsut give him an action to Force Blast or Quake the adjacent foe.
Another interesting idea - if you're worried someone will take him down to 3 legs, remember that if it's only a small hit you can simply choose NOT to use up a leg extension when you are hit. That way you still get to Colossal Retaliate for an extra placement and attack. And since the guy always has 3 damage he can always threaten even opponents with reducers.
Finally, don't forget that Quake with a single target is possible at his natural damage level of 3.

If only the extensions weren't so badly design. I'd love to have a tall stilt-man that stands actually upright.

Imagine a 300 point Stilt-man.....getting one shotted by a single target pulsewave. Ouch