They look cool and theyve been used in official demos but theyre probably not tournament legal
The most unusual thing about the Turtle deck is that it is Rainbow - using all 5 colours of mana (resource), which would typically dilute a deck to being unplayable (MTG Commander decks are at most 3 colour, ordinarily) - but is not only playable, but really good fun, with the turtles plus splinter (black) covering the 5
The main idea in this upgrade was to reduce the average cost of ink on cards, that is, to allow more characters in the starting turns without losing quality and presence at the board
If you have a way to give Earthquake Dragon haste, with say Concordant Crossroads or Lightning Greaves, for example, then your opponents will be staring down a 10/10 flyer with trample the turn it is played
The Vizier plays into that place nicely, and its just a simple four mana to play
Sarkhan aims to return the dragons of Tarkir to their former glory, believing they are the rightful authority on the plane