Whenever you cast a spell of the chosen type, copy that spell
Even better, Sword of Wealth and Power makes a Treasure token when the equipped creature deals combat damage to a player, and then you get to copy the next spell you cast this turn
With powerful synergies from sets like Throne of Eldraine and the Calvary Charge March of the Machine Commander deck, knights have access to aggressive strategies, strong typal support, and efficient creatures
The third deck, Paradox Power, is a Red/Blue/Green deck that will contain Doctors 12 and 13, as well as their companions
This allows you to bypass the "commander tax," as you aren't casting Derevi and the additional cost will not be applied
Its worth noting that these reprints include a healthy mix of merfolk-specific payoffs and generically good cards (Metallic Mimic, Thassa, God of the Sea)