Azkend 2: The World Beneath

This is actually one of the easier achievements in the game despite being a 100G achievement. To increase your multipler in the Time challenge mode, you need to make a match of at least 6 tiles which will set off your ball lightning. This will give the tile it strikes a gold ring around it. Using a gold ring tile in a match will increase your multiplier by 1.

There are an abundance of compasses in Time challenge and matches come very easily, so it's very likely you'll be able to get this achievement within 1-2 attempts. Just move quickly and always aim for 6+ chain matches to add more gold rings. Once you have no more long matches, match as many of the gold rings as you can. Just always give priority to the long matches and save the gold rings for when you run out.