Read about Defender's Quest
, played the web version for an hour, loved it, bought it.
You play a mage who places party members as you would in any tower defense game, except you don't have unlimited towers. You purchase party members and equipment in towns and place them as needed in battle. Some monsters hit back, some don't. Your character, the mage casts spells and when her health runs out you lose (I am guessing, haven't lost yet), she doesn't attack. Her mana is used to boost your party members stats/skills and to cast spells. Your party members level up and each class has a different, basic, skill tree to upgrade.
Graphics are nothing special to look at, sound effects are very minimal, and the music is decent. The interface has lots of keyboard shortcuts and you get used to it pretty quickly. Perfect laptop game.
$7, and get a dollar off if you enter "RPS" as the coupon code. Guess they submitted the game to steam but got rejected and are resubmitting. Very fun game, give the web version a try.