IP is for what???

So first off if this is the wrong board sorry, looked like the best option. So what am I supposed to use my IP on nowadays? I have all the champs, hextech drops keep me with enough champ shards that I can usually instaroll the new champ. I used to buy runes but I've got most any I'd want at this point and rune pages seem like a waste since they wont be around much longer (and I have 8 already). So apart from the occasional icon once in a blue moon what is IP even good for?

P.S. please let me buy keys with IP, I'm sitting on 9 chests because key drop rate is bad.