Rulings

• 2018-12-07
  Vengevine’s ability triggers only for the second creature spell you cast in a turn. It won’t trigger for the third, fourth, or so on. It also doesn’t matter how many noncreature spells you cast in a turn; the ability counts only the creature spells.
• 2018-12-07
  Vengevine’s triggered ability checks the spells you cast over the course of the entire turn, not just the ones you cast while Vengevine is in your graveyard. For example, if you cast a creature spell, then Vengevine is put into your graveyard, then you cast another creature spell, Vengevine’s ability triggers.
• 2018-12-07
  Vengevine’s triggered ability works only if Vengevine is already in your graveyard as you finish casting your second creature spell in a turn and if it remains there until the ability resolves.
• 2018-12-07
  If you cast your second creature spell in a turn and Vengevine is in your graveyard, Vengevine’s second ability triggers and goes on the stack on top of that spell. The ability will resolve, allowing you to return Vengevine to the battlefield before the creature spell resolves. The ability resolves even if that creature spell is countered.