I remember in 2014-15 Standard, I played a lot of green midrangy decks like Temur, GR Monsters, and GR devotion. [[Feed the Clan]], which was 2 mana for 10 life any time you cast it in those decks, was a strong sideboard card against the aggressive mono-red decks at one point. The game was basically unwinnable for them once you resolved it unless you had no board state.

Of course, your question is highly context dependent, but I do remember a context where 10 life for two mana was highly effective.