Harbinger of the Seas + Curse of Marit Lage

Harbinger of the Seas

Curse of Marit Lage

How it works

1. Because Harbinger of the Seas causes all nonbasic lands to be Islands, and Curse of Marit Lage prevents Islands from untapping during their controller's untap steps, nonbasic lands do not untap during their controller's untap steps.

This potent lock exploits land type modification to utterly freeze your opponents' mana bases. By deploying Harbinger of the Seas, every nonbasic land in play loses its original identity and becomes a basic Island, neatly stripping away utility lands and fixing. Once this transformation is complete, Curse of Marit Lage immediately triggers to tap all of those newly minted Islands and permanently pins them down, ensuring they never untap during their controllers' untap steps.