If this card is destroyed by battle and sent to the GY: Special Summon 1 "Troop Dragon" from your Deck.
Rulings
Netrep Q&As
Q: When the third "Troop Dragon" is destroyed, is your opponent allowed to inspect your deck to verify that you do not have another "Troop Dragon" to Special Summon? A: Yes they can. It should not take long to do this. The Deck would need to be shuffled afterwards, naturally. Curtis Schultz, 02/01/2004