Dota anyone?

[Douglas]

25, actually. All but one hero follow a simple pattern: 3 normal abilities with 4 levels each, which require a minimum hero level of 1/3/5/7 to learn; 1 ultimate ability with 3 levels, which require minimum hero level 6/11/16 to learn; 10 levels of attribute bonus, each level giving +2 to all attributes and requiring 2 more hero levels than the one before. At level 25 you will have all of these maxed out.

The single exception is the Invoker. He gets a little complicated, with three 7-level reagent abilities and a 4-level "ultimate" that gives you a spell depending on which reagents you currently have active. There are 8 different spells that Invoke can grant, and you can eventually have any 2 of them available at a time. He is Not Recommended for new players.