Noting that there is currently an ideas thread for this draft here: http://www.scp-wiki.net/forum/t-9926810/very-odd-scp:the-bell-snake
Author, you really should have revised your concept and then confirmed that the changes you made were actually an improvement, rather than jumping immediately into the draft.
What you have here is a pretty classic example of a generic monster, with tacked on danger elements and random attributes (why does it need a bell anyway? How is a bell related to a weird reincarnation/rejuvenation cycle and fusing with weapons?) that just make this seem like a jumble of unrelated details that end up being confusing and unenjoyable to read about. Why are so many MTFs necessary for this thing? If the Foundation realized that bad things happen to it when it dies, why didn't they just keep it in some sort of suspended state like cold storage or the like? Why is it a Wondertainment object if it's clearly not kid-friendly at all and seems to encourage kids to kill their pets in order to see what new thing it becomes next?
Furthermore, you have a ton of nonsensical and pretty random containment that just makes the Foundation look kind of dumb. Why does the terrarium need to be exactly sized? Why does this thing need an exact cube containment cell that's 12 meters (~39 feet in height), taller than a 3-story-building? I recommend reading this guide on containment to get a feel for how to write more logical, resource-conserving procedures.
Definitely needs another round of brainstorming. Most of this is pretty unworkable and comes off as overly silly as a result.