What is Amazon Underground?
Underground is available as a stand-alone app for most Android Devices. It essentially allows you to download select apps for free and/or activate in-app purchases for free. Right now this service is free for anyone that wants to sign up. Amazon pays devs based on how much time users spend playing the game. Amazon's goals are unclear at the moment.
http://www.amazon.com/Amazon-com-Amazon-Underground/dp/B004GJDQT8
I'm an apple user, but I use an android emulator to buy ICE this way. It's a little complex but it does save money. Basically, it's like buying a gift card but one that is always discounted. Here's what you have to do: Step 1: Download the Amazon Underground app: https://www.amazon.com/Amazon-com-Amazon-Underground/dp/B004GJDQT8
Step 2: Download Vainglory through Amazon. This is an important step! It may also require you to delete your existing vainglory app.
Step 3: Buy coins. The more coins you buy, the bigger the discount. https://www.amazon.com/gp/aw/d/B0096E8DSM/ref=mp_s_a_1_2?ie=UTF8&qid=1467298940&sr=8-2&pi=SY200_QL40&keywords=amazon+coins&dpPl=1&dpID=418TAh9NMuL&ref=plSrch
Step 4: buy ice in the version of VG you got from the Amazon store.
It should automatically use your coins. I believe that using your coins on ICE gets you 5% back in coins also so that can add up after a while