If you are somehow generating one toughness tokens then it is incredibly efficient but even when your not it still offers great value and a variety of applications above and beyond pure card advantage
The new Spellbook ability is only on a handful of cards created as a part of Alchemy: Innistrad
This deck doesnt focus on Toxic, Infect or Poison, but it has enough proliferation from the commander zone that you might consider a card here and there
Magic: The Gathering, developed by Wizards of the Coast, is the worlds most popular trading card game
My favorite is Curious Forager, with its magical staff and cute druid outfit
If at that time the greatest toughness among creatures you control is 0 or less (probably because all of your other creatures were destroyed or otherwise left the battlefield in response), you won't gain any life