I know I am late to the party here, but I read through the whole thread and didn't see this mentioned...
I have been farming Arena Bronze with a mono death deck. I put in a single Cloak 50 or so games ago and I have been using it a fair bit:
Want to protect your Dragons from those pesky Reverse Times? Cloak them.
Need a quick and dirty way to pseudo-burrow your Devourers? Cloak.
Need your opponent to waste a Deflagration instead of use it on your Vampire Stiletto? Cloak it.
So that's all fantastic, but it also has, what I consider to be, a bug: If Cloak is Stolen from you, no matter how many turns you had left on it, it reverts to 3 turns for the new owner. Then if it is stolen again it resets again. So it seems a single Cloak can go on indefinitely. I think it should keep counting down its original number like a Dimensional Shield.