S6E1 THE RULES

In the premiere of Season 6, we get some confirmation of the Rules of the Island:
1. Jacob and MIB cannot directly harm or kill each other; they need an outside agency (using that person's own free will) to kill each other.
2. Flocke is MIB who is also Smokey, the black smoke monster who can kill or destroy.
3. A ring of ash is a protective barrier against Smokey. It keeps the monster outside the ring. (Seen before around Jacob's cabin - - - but the ring was broken and Jacob fled to the statue foot.)

But there are some troubling inconsistencies, too.

1. Jacob could be killed by a metal object(knife), while Flocke could not be killed by a metal object (bullet) by Bram's machine guns. The exception could be that Jacob (as RA) was powerless at night (when he was killed) but MIB's power has been shown both during the day and night.
2. Christian's body was missing after the 815 crash, but his ghost roamed the island speaking to various people. Locke's body was not missing after the 316 crash, but MIB used it (shape shifter). MIB as Smokey killed Rousseau crew, then reconstituted them on the beach where Rousseau killed them because of their sickness. It infers MIB can mold multiple, mortal bodies but someone can mold one bullet proof Flocke body.