If you're a fan of both tower defense games and dungeon building ones, then a game that combines the best things about those two should be right up your alley. Wicked Lair is one of the newest games that is a hybrid of those two, and it should keep you glued to your smartphone for some time (or at least until you get tired of it).
The object of the game is to dig deep and build a dungeon as deep as you can, all while training your minions (no, not those cute yellow things from Despicable Me) to fight against heroes that will try to penetrate your territory. These are terrifying monsters and powerful creatures who are hell bent on preventing the heroes from stealing your loot.
You can also send your creatures to go out and destroy the towns that are sending the heroes to your lair. And because you're not the "good guys" in this game, you get to loot and burn the said towns in order to prevent them from spawning any more adventurers. There are 9 different dungeon types, plus 100 different creatures to both defend your dungeons and attack the towns. You can also add extra layers to your dungeon as the game progresses and you get more money.
Visually speaking, the game has a kind of retro look, but also the graphics are nothing to complain about. It's not that difficult of a game, especially if you're already familiar with tower defense, dungeon building, and even a little bit of RPG. You can download Wicked Lair for free, but with in-app purchases available, from the Google Play Store.