So far they announced 3...
I'm sure there will be more though, and they explained since they are items that drop, they are also effected by rarity/strength. So each can drop as minor and major (or however many variants of each).
So a minor multistrike rune would make skull of flame skill bounce once, while major would make it bounce two or more times (not exactly sure on specifics).
Ok, there's more info out there than I knew about...
I guess there might even be a chance for more as the game progress too...personally I think it's an awesome idea, and definitely and evolution in terms of gameplay.Originally Posted by Article