Sion glitch/exploit 2.5 attack speed, -200 AP

Good afternoon summoners, not sure how many people have heard about this, but there's a glitch going on involving Sion + Guinsoo's Rageblade. Basically, if you toggle Sion's E on, he gains 2 stacks from rageblade,  but it doesn't add extra AP or AS. It does deduct it when the stacks expire though, so you lose 6 AP and AS when the stacks expire.

When you get to under -200 AP, your AS goes to under 0, which causes a math error and sends your AS to 2.5. Afterwards, sell rageblade and build pure damage items. If you use your ult it removes the 2.5 speed unless you get get your AP really really low first, around -250 to -280ish

Overall it takes about 30 minutes and you're pretty much useless while you do this since your shield and stun will do 0 damage and your attack speed will be a complete joke until you hit the sweet spot. Below is a video of some guy using it in a custom game.

EDIT: Glitch was patched