Every color has the ability to deal with this.
Scour from Existence will kill the Octopus in all colors. Anything with Ingest will convert green / blue gems to void, possibly slowing Kiora down.
White can disable and/or Kill the Octopus.
Blue can bounce, disable or kill the Octopus, or cast its own Crush of Tentacles if possible.
Black can kill the Octopus, and force discard of the larger spells while they’re still in hand.
Red can destroy the support, possibly burn the Octopus (though Scour from Existence works better), and also throw down Berserker creatures in a hurry.
Green can reset the board with The Great Aurora (subject to availability), destroy the support, and possibly throw down some beefy creatures to deal with the Octopus (or, Scour from Existence).
I played against a Kiora deck which had Crush of Tentacles. It would throw down a bunch of fat creatures, destroy them with its own Crush of Tentacles, and then just as its octopus was poised to attack, kill it by using another Crush of Tentacles.
Scour from Existence costs 12, so unless I’m preparing for this and not setting up my board, I’m not gonna be able to Scour in one turn. Plus, even if I do, Kiora gets access to another Crush of Tentacles very quickly from the card draw.
White and Blue can disable it, sure, but Kiora gets so many matches that their supports that disable will be gone very quickly.
Black’s discard is ineffective because Prism Array just draws her hand back, so unless I had some way to KEEP her hand empty (which is almost impossible turn after turn when she’s refilling).
Red can’t burn the octopus, don’t be ridiculous. Red can use board destruction to get rid of the supports, on a good day when it draws the right cards. Red is probably the best at defeating this Kiora deck.
Green’s creatures don’t match up well with the octopus OR with Crush of Tentacles bouncing them. If they’re big enough to do anything, they’ll be too expensive to replay; and if they’re small enough to replay, they won’t affect the board with Octo in play. Sure, if I draw a 1-of Great Aurora (which I don’t have, but even if I did) then I can kill the supports, and then still not be able to kill my opponent in time before they can get the combo rolling again.
this, my friend, is one of the reasons why kiora costs 950 crystals to buy
Costing crystals (aka real money, for most people) shouldn’t be a reason to do broken things. Doing cool and exciting things is all great, and I am all for letting people pay extra to get amazing things, but it still has to be balanced. In paper magic, Tarmogoyf costs 150-200$, and it still isn’t BROKEN. It dies to almost all removal in the format, and can be dealt with by any deck that wants to.
Bottom line is, yes the game is imbalanced, and no-one really gives a toss.
Clearly, at least I do. And if I do, then there are some others that do. I would venture a guess that most people DO care, they just have given up. I do not plan to give up, because I want a game that’s fun for everyone, not a game that’s super imbalanced and fun only until you play against the one walker that people pay way more money for.
Being totally honest and looking at all cards everyone has available, Kiora simply has access to too many super powerful spells and can ramp to them, making her broken. No one can deal with a well built Kiora deck unless you build the deck SPECIFICALLY to fight Kiora (in which case you’re worse against everything else). That is the definition of format breaking, and needs to be fixed.