This is one of the "special" items... I forget what Chris is calling them. I think he mentioned the name in his recent video of the game. I "believe" they might be called "Incredibilities". They exist to massively change the game. Many of them were actually my idea, including this one, so they can get kinda devious, hah. You can only have one item of this type at a time though, since they take up the attachment slot. I dont know how many are implemented right now, this is the only one I've actually seen in-game so far. If you've seen it, I'm guessing you've figured out how to make them appear. I do think the method needs to be a bit harder to do, but I'm not entirely sure just what to suggest yet.
Risky Assassin is meant to basically allow you to be a sniper, taking out enemies from safe places, but it puts you at heavy risk the whole time.
The description of it, taken directly from the design document, is this:
Big damage increase, big range increase, attacks from your main gun now bounce if they didn't already. Upon entering a room, you are invincible and unnoticed by enemies for a few seconds or until you fire. You have no shields at all and you are reduced to 1 HP and no missiles at the beginning of a floor, but health/missile pickups will drop as normal. You are immune to hazards.
Health items suddenly became alot more common in a recent build, so I might suggest that an additional penalty be applied to this item.
