Dimensional Rift

Shouldn't this card be restricted, so it can't be combined with Marcus Jamburg?

Jamburg+Rift is a fearsome combo.  But it's not a fast combo, nor an insurmountable combo.

Jamburg has been restricted for excess power, without restriction he would be too common (much like eg sewer rats). But plague stone and ice shaft are as much as issues with him as the Rift is, and restricting all decent once-use supports is hardly attractive.

Non-wounding or multi-wounding character removal, will take him out. Support destruction that doesn't send to the discard, such as Raid. Textbox blanking.

Or just plain winning before they can get it going.

I disagree about it being as much a problem as with Plague Stone and Ice Shaft.  The Stone hardly combos with Jamburg at all because it shuffles back into the deck after one use.  The Jamburg+Shaft combo is kind of a smaller-scale version of Jamburg+Rift, amounting to "Pay 3 to destroy one small-to-medium sized guy."

The Jamburg+Rift combo basically becomes a repeatable "Pay 3+3 to destroy everything but Marcus Jamburg."  Add in the fact that he's got Toughness to make him harder to kill, and he's got an Investigation icon that makes him lethal when no one's around to oppose him at stories.

You're right, it's not insurmountable, and it is slow.  And I get what you're saying that they restricted Jamburg, so he doesn't become ubiquitous.  And admittedly, I've never seen a CoC tournament.  I'm just surprised that turning Jamburg into a nuclear arms dealer, when he has built-in immunity to his own infinite supply of nukes, isn't considered broken.  Maybe I'll go ahead and take advantage!