Sangen Summoning

“During your Main Phase 1, FIRE Dragon monsters you control are unaffected by your opponent's activated effects. During your Main Phase: You can add 1 "Tenpai Dragon" monster from your Deck to your hand, then discard 1 card. You can only use this effect of "Sangen Summoning" once per turn. If this card is destroyed during the Battle Phase: You can target 1 Dragon Synchro Monster you control; double its ATK.”