I used to use Whispersilk Cloak in an early version of my Alesha, Who Smiles at Death deck a few years ago, but the 5 total mana to cast and equip felt kinda clunky for me
Obviously, I wont mention cards that are reprints, like Super Rod or Counter Catcher, since they were already in the Expanded card pool
Considering extra combat steps are usually a lot more expensive than this, its no wonder that Grim Reapers Sprint is so popular
Generally, its trivially easy to make sure this wont backfire, and even if it does, theyre now spending 2 mana on your turn for a spell that they just watched you cast for 1 mana
The SIR version higher up the list runs significantly higher, which takes us back to the MHR vs SIR debate