The Titan mechanic looks pretty interesting. Yes – that means 20 damage burn if he sticks around for 2 turns after you play him. On the other hand, Norgannon‘s abilities start pretty weak, but every time you select one, the others double in power. For example – Eonar, the Life-Binder will summon a 5/5 Taunt every time you select one. On top of the abilities themselves, Titans also come with a special effect that triggers when you use those abilities.
However, keep in mind that those will be the highest priority removal targets for your opponent, so it’s quite unlikely that they stick for multiple turns unless you somehow protect them. Once you use all three, the minion goes back to normal and you can attack with it like with any other. Once the ability is used, you can’t use it again. You can do that on the turn you play them too. Their gimmick is that instead of attacking, when you click on them, you select one of the three abilities. Each class is getting a Legendary Titan Card with varying costs and effects. Titan is the “titular” mechanic of the expansion.