I have ONE word for blitzcrank Mid Game. (Assuming you killed your lane and the tower is down)
Your bot lane should have been a kill lane and should have owned your lane.
Ward the river or the tribush, so that your ad carry is confident with being alone in the bot lane.
***(Your bot lane should be pushed when you do this)***
Go run around the map and spam abilities to charge up your Tear ASAP, don't be afraid to spam your skills at any enemies you see when you are roaming with your jungler or mid laner.
It is HIGHLY recommended you roam with a jungler with some CC
Roam with a mid laner who can push lane really hard and can have global presence or just really good for roaming.
Since Lane Swaps are sooo mainstream now, you can lane swap and deny the enemy ADC/Supp from farming if you lane swapped earlier.
Lane swap so that the enemy top laner gets zoned completely out of experience range and also cs range.
Go Gank Mid, go ward their jungle, go steal their jungle, take dragon control.
Support, that is the meaning of support, have wards all over the map. Support your team.
Try and catch a few members off guard, most likely their mid laner or the jungler if they are near the bot lane. Always stick with your mid laner/jungler who has CC or just take someone with you who can roam really welll in general. Be a threat, show your presence in lane and also out of lane.
Make sure to farm for