Hearthpwn

The interaction makes perfect sense when you know what's going on. (I'm not saying I agree with it; I'm just saying it makes sense.)

You just have to understand the order in which the auras are applied. Before that, you have to understand that nothing -- absolutely NOTHING -- in the game happens simultaneously. It is impossible. For any two effects you care to name, one must be applied before the other, even if it seems like they should be happening at the same time.

For Summoning Portal and Mechwarper, you just need to know that Summoning Portal's effect is always applied first, before any other aura. I don't know why, but when Summoning Portal was created, it was decided that its effect should always come first.

The result is that Summoning Portal reduces all costs, but not less than 1. At that point, its job is done, and the game stops caring about Summoning Portal's "not less than (1)" clause. If another aura reduces mana costs, it is the additional aura, not Summoning Portal, that is further reducing the cost. So Summoning Portal is not breaking its own rule, and the additional aura doesn't care about the Portal's limitation.

Obviously, though, it's a problem that the interaction allows for an infinite combo. That's exactly the sort of thing that needs to be addressed when a card with infinite potential (e.g., any Echo card) is added to the game. But don't expect Blizzard to worry too much about anything that's happening in Wild. They can't even be bothered to fix the nightmare that is Standard ever since they brought Wild cards back to that format.