Can you react to your own 'When you play me' trigger with a spell, and does En Garde give +2 might to Carnivorous Snapvine when it's the only unit at your base?

Ruling: Yes, you can react to your own "When you play me" trigger. En Garde will give Carnivorous Snapvine +2 might total (+1 base, +1 additional) because Snapvine is the only unit at your base.

Sequence:

• Play Carnivorous Snapvine
• Its "When you play me" trigger starts a chain
• As active player, you get priority and can play En Garde as a Reaction
• En Garde resolves, giving Snapvine +2 might (since it's the only unit at your base)
• Snapvine's damage ability resolves with 8 might total
• Snapvine and Anivia trade evenly at 8 might each

Nuances:

• En Garde checks if the unit is the only one "there" which doesn't specifically mean battlefield, so it applies when Snapvine is alone at your base