Gambits

Tunnel's reaction triggers whenever you discard it outside Clean-up — Warehouse/Embassy/Storeroom-style sifters do that constantly.

Tunnel/Village Green/Faithful Hound-style discard payoffs trigger constantly alongside heavy sifters, extending the sourced Tunnel + sifter pairing.

Crossroads/Shepherd-style payoffs for revealing/discarding Victory cards pair naturally with Gardens/Silk Road-style rush plans.