it offers you so much value that it's best to think of it as an enchantment that costs no mana, at the expense of skipping a land-drop for the turn
While the One Ring is more versatile, being a colorless artifact spell that can go into any deck with space for it, Orcish Bowmasters is just as format-warping, making it really hard to play one mana creatures and punishing card draw hard
Mew Ex and Yanmega Ex are great because they don't require a specific Energy type to attack
If you don't control an Army, create a 0/0 black Zombie Army creature token first.) In the rare case that you control multiple Army creatures (perhaps because you played a creature with changeling) while you amass Zombies, you choose which of your Army creatures to put the +1/+1 counters on
Add to that the ability to search up any two lands, say Dark Depths and Thespian's Stage, and it becomes apparent just how powerful Prime Time really is