Lightning Helix "Basically the awesomest card ever." Life gain gets no respect, because when you invest mana and cards in life gain it has the nasty habit of not making a difference, especially when you're trying to play a burn-heavy game, which either involves trying to burn out an opponent or all opposing creatures
Mathematicians much smarter than myself have done the analysis for us, and my experience tells me that it works out
This alternate art is gorgeous, so it will definitely become a collectible item
Murders at Karlov Manors Duskana, the Rage Mother, and Modern Horizons 3s Kudo, King Among Bears both play into Bears classic 2/2 stats
Playing this in your second main phase after something died in combat is going to feel pretty good, as at that point Denethor is a three mana 2/4 and a 1/1 token, which is an amazing rate