Death's Shadow's bigger cousin? Seems solid. Works with both players' life totals, and you don't need to put quite as much work into getting a low enough life total just to have it live (which makes it more relevant in standard, given the lack of shocks and fetchlands to lower your life total).
Hard to know if this would see Modern play - I would assume so, just based on the success Death's Shadow has had, but I don't have enough familiarity with the format to know how relevant +7+7 is compared to the additional mana cost.
Looking to commander, the kicker makes it somewhat useful, but it's ultimately just a vanilla(ish) beater that you can't play out early. Being a */* instead of a 13/13 also means you can't make use of it with stuff like
Varolz, the Scar-Striped. I'd probably go with
Torgaar, Famine Incarnate if I wanted to halve some life totals.
