When in there and you control a Mountain, all creatures you control will have haste
Well have to go in with a plan to either make sure there are lots of counters on it, or, more likely in black, a sacrifice outlet should things start to get too hairy
Raiyuu, Storms Edge If you specifically want to build around samurai as a creature type, Isshin, Two Heavens as One definitely works, though Raiyuu, Storm's Edge is friendlier on the budget
Sturdy to Withstand Heavy Play & Shuffle: Excellent quality card sleeves, make sure you have no issue with them splitting or slipping when shuffling
If there aren't any spells worth countering in a given turn, you ideally be able to draw some cards at instant speed while making more tokens
It also makes 'black and red spell considered colorless damage', which is a rather specific way to prevent them from being countered by counterspells that cares about a specific colour