The IGG loop is simple Infernal Tutor + enough mana to cast it and 2x Lion's Eye Diamonds. Ideally this is a situation where Ad nauseam is good. With only access to 1x IGG MD and a little mana short you just fetch out AdN and win, but if you have 5 spells + IGG then it makes for 11 storm. Storm count 4, play IT (5), put it on the stack and blow up LEDs for 6 black, fetch out IGG and cast it (6), bring back LED, LED, IT, play both LEDs (8), cast IT (9), place it on the stack and blow up LEDs for 6 black, fetch out IT and cast it (10) then fetch out Tendrils (11). Just practice with the deck, this varies, sometimes you have enough mana to IT -> BW -> IGG and can get sick storm by just fetching out Burning Wishes and getting IGG back. The IGG loop can also be achieved LED, Dark Ritual, IT and a few mana floating but most of the time you are have 5-4 man floating and can't get the extra IT/BW in so it goes for 1 less storm.

Diminishing Returns is great when you are in serious troubles from hand destruction, maybe your acceleration is lacking, it is also wise to use this against burn since AdN can get you into multiple Bolt + Fireblast range.