Once per turn: You can send 1 face-up "Triamid" card you control to the Graveyard, then target 1 Set Card on the field; destroy it. Once per turn, during your opponent's turn: You can target 1 "Triamid" Field Spell Card in your Field Zone; send it to the Graveyard, and if you do, activate 1 "Triamid" Field Spell Card from your Deck with a different name (this is a Quick Effect).
Here are the Triamid Field Spells you can search with Triamid Master’s second effect. Triamid Fortress is for your opponent’s turn, Triamid Cruiser is for your Main Phase, and Triamid Kingolem is for your Battle Phase so search your Field Spells with this in mind. Although Triamid Kingolem can be better than Triamid Fortress even during your opponent’s turn.