Ok, first things first: This game requires an internet connection to activate the game. Though I usually hate this, it wasn't a painful experience like it is on some other games. You get online to punch in the code, and that's about it.
Clash of Heroes takes the M&M style of gameplay and turns it into a version of Bejewelled. There are different units with different attack types and special abilities, and also attack in different turns. As you play more, you unlock bigger creatures that can turn the game. Though the game is easy to understand (get 3 of the same color vertically to attack or horizontally to build a wall), the combinations of the units themselves, and attempting to chain attacks with the number of moves you have makes the game into a very interesting tactical game. Combined with the Anime style graphics, the game is visually good.
For the $5 spent at Mighty Ape, the price to the amount of hours you will spend on this makes it a very worthwhile game.