If you gain an amount of life "for each" of something, that life is gained as one event and Essence Channeler's second ability triggers only once
Sacrificing a creature per scry is a steep cost, but the second ability helps to recoup your losses
For now though, it seems like all four are worth checking out
So long as you can keep him protected, or can bring him back with Cruella's ability, he can truly tip the scales or serve as a lightning rod for your opponent's ire while your other cards mop up
XY Evolutions This one sits at a market price of $6,250 per case but is agreed upon to be a very meh set
Getting around pesky indestructible effects, whilst also helping you along if you have anything at all that cares about people sacrificing their stuff, its not difficult to see why this colorless sorcery made it so far up the list