Dragons of Tarkir: mechanics

Dragons of Tarkir set is on the way, hence it is high time to introduce new mechanics:

Rebound - lets you cast an instant or sorcery spell a second time for free during your next upkeep. If you cast a spell with rebound from your hand, you exile it instead of putting it into your graveyard. Rebound works only if the spell resolves. This is the new Jeskai mechanic, which for the first time appeared in Rise of Eldrazi set.

Formidable - an ability that allows you to do something if the total of power among creatures you control is 8 or greater. This is the new Temur ability.

Exploit - an ability which states that when this creature enters the battlefield, you may sacrifice a creature. It says on the card what happens if you exploit. This is the new Sultai ability.

Megamorph - if you turn a face-down creature with megamorph face up by paying its megamorph cost, you put an extra +1/+1 counter on this creature. Turning a creature face-up doesn't use the stack and it can't be responded to. All clans have this mechanic.