He was attacking with this card, and I blocked it with two creatures because of the double strike. My opponent USED THE ACTIVE ABILITY which clearly says TAP Seasoned Hallowblade. His attack
Double Strike in MTG - Rules, Best Cards + Decks!
Double Strike in MTG - Rules, Best Cards + Decks!
Double strike probs — MTG Q&A
Double Strike in MTG: Rules, History, and Best Cards - Draftsim
Double Strike in MTG - Rules, Best Cards + Decks!
First Strike & Double Strike - MTG Keywords Explained - Card Kingdom Blog