Exxaxl: The borderless printing is very busy with its art
From memory Shadowspear was around five USD the first few weeks after THB released Because of its relevance in the Theros story arc, I think were mainly going to see it getting reprinted in supplemental sets or universes beyond sets because reprinting it in Amonkhet or Lorwyn would make little sense
(It's an artifact with ", Sacrifice this token: Add one mana of any color.") Amass Orcs 2
Individual bending abilities like Waterbend, Earthbend, Firebend, and Airbend can work outside the set, sure but Avatar Aang himself becomes much harder to build around effectively, especially if your goal is flipping him consistently
Culling the Weak Weve looked at a few cards that sacrifice creatures to generate mana, but Culling the Weak does it the best because it turns a creature of any size into 4 mana