one piece the best booster box PRB-01 such as Mihawk from OP PRB01 Booster Boxes are HERE!!

More recently, theres The Archimandrite from The Brothers War Commander that gains you life on upkeep based on the number of cards in your hand

Interceptor seems like a perfect fit for many of the new school Mardu legendary decks

The March is a cheap sorcery that copies an artifact creature you control, so it's cheaper but more limited since just artifact creatures that you control are copied

In Commander, youre pretty safe picking a lower number, like two or three to try and guess what your opponents are playing

but thats no cost, so think its fine

Uncommons & Commons Golden-Tail Trainer Starting with a reduction of one mana for Aura and Equipment spells and then scaling up from there is solid