If your opponent casts Murder on one of your creatures, you either prevent it from happening or get to do it to one of their creatures
They form a viable strategy without being too broken, and most of them are great additions in other decks
But if your approach is to bide your time, powerful spells like Necropotence can be game-changing despite their steeper life cost
You dont need another card to banish Pawpsicle in order to use this effect, and the healing capability wont work if you happen to banish Pawpsicle via another effect like Flavershams Artificer ability
It can eventually become a win condition of sorts, but Sanctum of Stone Fangs and Honden of Infinite Rage do the same thing a lot more efficiently
Cards like Secret Rendezvous and Sky Crier just feel bad, no matter how much people might say it is a good political tool in Commander