Tales of Middle-earth is advertised by Wizards of the Coast as being built around the ten color pairs, but there is a significant amount of overlap into a third color for most of these, if not an almost identical second pair that will likely blur together into a single archetype given how plentiful the fixing is
Thassa, God of the Sea seems like it would be great in a go-wide merfolk deck, and it does have a place there because its activated ability helps with Coastal Piracy types of effects
With more than respectable stats of 6000 power for 5 DON!!, Marco will KO an opposing character with a power equal to or less than 3000
Alchemy is one example, as you wont be able to play it on Magic Online or in paper
If you have cards valued over $5.00 then you will eligible to be paid on a percentage base
As for how that color choice influenced his art, we did ask for his sword, Glamdring, to have bluish energy, and the setting of Moria lends a red glow to everything