mtg tax cards Land — Masters Edition III (ME3) | Card create a number of Treasure tokens equal to the amount of mana they paid Land Tax | Commander Masters

These are typically very old cards because age tends to correlate with scarcity, especially with the Reserved List hanging around

Other options in regards to Gruul dragons matter legendary creatures seem quite limited, and the fact Vrondiss, Rage of Ancients and Klauth, Unrivaled Ancient were both in a precon not too long ago likely means they wont show up either

Pack it full of early mana ramp like Mind Stone and Arcane Signet and some Haste enablers like Swiftfoot Boots and you are off to the races

Mana Base New Lands Reliquary Tower is a classic land that could be in almost 100% of the Commander decks nowadays, after all, not everyone likes losing resources due to excess cards in hand

The Convergence of Dominion even helps put cards in your graveyard directly from your library, a mechanic called mill, with its Translocation Protocols ability, milling three cards and building your undead army