Instead, you can substitute with True Conviction ($4) for permanent double strike and lifelink rather than just a temporary buff
The implication is that Mewtwo's raw abilities were powerful enough that even its creators felt the need to dampen them before they could be used safely
Rebbec, Architect of Ascension Rebbec, Architect of Ascension grants a pretty wide swath of protection from spot removal, which is a useful service for the artifact commanders that might want a spot of white to partner with this artificer, like Silas Renn, Seeker Adept, Ich-Tekik, Salvage Splicer, and a few others
This is a commander that is begging to lead a Simic big-mana deck, full of Eldrazi and massive blue spells
It costs 2, so can be sung as early as turn 3 (or even turn 2 if you play Cinderella - Ballroom Sensation) and it draws you 2 cards