It's all perfectly serviceable stuff
This inexhaustible supply of cannon fodder allows black to eke out incremental advantages and dominate combat just as effectively as greens enormous monsters
With firebending, this can become a powerful creature on its own, and it technically repays for 66% of its mana cost the turn it's played, as it costs 6 mana but generates 4 with firebending
Land tokens are a fairly elegant solution to this, adding more mana without asking players to delve into their decks for a minute or more
Boom Scholar, in particular, can reduce the cost of exhaust abilities from other permanents, further accelerating your game plan
Mark Rosewater gave a 'mega-teaser' hinting at what was in this set on Monday, September 19