Dimir Excruciator is a discard-and-removal deck (Duress, Deceit, Bitter Triumph, Requiting Hex) that wants to strip our hand and pick off threats one at a time, so Defend the Rider's hexproof/indestructible mode protects our best threat from their removal suite. Soul-Guide Lantern exiles a card from their graveyard on entry, disrupting their Bitter Triumph discard synergy and denying recursion value, while its sacrifice ability can wipe their whole yard if needed. Spell Pierce is weak here since they have plenty of mana by the time they cast their key spells and the deck isn't spell-dense early. Terrian, World Tyrant and one Lumbering Worldwagon come out as they're slow against a deck full of efficient one-for-one removal that trades up easily into our bigger threats.