use all light troops. use cannon special troops. play in world 76, and play the siege scenario. immediately send all your troops to attack the wall. once the clock displays 26 minutes remaining, cannon out your troops. if you are speedy you will get 12 rank in about 55 minutes if you lose every time - occasionally all 4 players are using light troops and you may win first place for two ranks instead of one. berserker (i), archer (i), seers (i), dragonstone (i), and arguably onyx (i) over 1.5 million i couldn't tell you for sure, but 4 for 3 is about as good as you will find. you may opt for items with a higher gp value if you don't want to wait several weeks to purchase all the fire runes you need. consider this rs wiki calculator, but i am not sure if the investment credit values change or not. the best betting strategy is to bet max - you will want extra reward credits to replace rings if you lose them and possibly for the cosmetic rewards - you would be kicking yourself later if you skimped on the few million gp in investments, then found out later you need more reward tokens and had to waste additional hours at MA. using this strategy you will need 3750k investment credits, which will cost about 2.8m at the 3:4 exchange rate for fire runes.