Humble Defector is an interesting option to consider
You will rarely find them in Play boosters, but always find one in a Collector booster
How much do Sword & Shield cards sell for
Instead of having to draw a specific card dedicated to being a resource and play it each turn, or generating a set amount of resource as per Legend of the Five Rings, the game is a constant back and forth of giving and taking memory, trying to be efficient in your moves and denying your opponent as much memory as possible to use on their turn
You can only use this effect of "Time Thief Double Barrel" once per turn
Valakut, the Molten Pinnacle Mono-red decks can get Valakut, the Molten Pinnacle up and running without much trouble, though multicolor decks are going to need Prismatic Omen or some similar effect to make this happen regularly