This card is surprisingly on the edge of playable. Getting to turn all your burn or kills spells that remove blockers into essentially Searing Blood is potentially pretty powerful. Don't forget that even if something goes down that Altac Bloodseeker gains its ability after first strike damage has happened, it still gets to deal damage normally in that case.
Are there still a lot of enchantments coming out of Theros block? Yup. Still further enchantments like Detention Sphere and Underworld Connections that you'd like to blow up? Indeed. Is hexproof still a fringe playable deck? So yeah, Back to Nature is going to put some serious sideboard work in. That your sideboard hate can be a complete blowout makes it that much better.
While the 1/1 body is a little lackluster, the repeatable locking down of a blocker is quite strong. Combine this with efficient pumps and cards like Madcap Skills and combat will become a nightmare for your opponent. Those key blockers they were depending on to stabilize won't cut it, and they certainly won't be able to race your team of small aggressive red creatures. The more midrange creature decks there are the better this card is. Expect at least of pair of these to show up in most mono-red aggro or Sligh decks.
Red White burn is already a popular deck. While this is a little slower to cast than many of the other burn spells, unless you work Young Pyromancer to the list, the big upside is taking your 4 damage spell count from 8 to 12. Now you only need to draw a combination of 5 Warleader's Helix, Boros Charm or Stoke the Flames to get a kill, and having that ratio compared to the 7 cards for 3 damage is quite nice. When all you're trying to do is count to 20, the extra point of damage really starts to add up. Drawing even 3 of your 4 damage spells is like casting a free Lightning Strike.