You may play any card or cast any spell during either of your main phases
There are a number of resources out there that allow you to plug in your decklist and get a breakdown of what percentage of your cards need specific colors of mana, what the average converted mana cost of your cards is, and other helpful information (Im partial to Tapped Out personally)
While it seems unlikely that another printing at Mythic Rare will do much to put a dent in the hefty price tag that comes with this card, Im very satisfied with the amazing new artwork by the inimitable Richard Kane Ferguson
It is also modular in that you can choose any two commanders with the partner keyword, not a specific coupling, so Bruse Tarl, Boorish Herder can partner up with Kydele, Chosen of Kruphix, Sidar Kondo of Jamuraa, or anyone else with the partner keyword
Formats: Commander (primary) | Competitive rating: Medium across formats, high for collectors 6
My second instinct was to count how many legs it had, but from a safer distance