Building your deck can be challenging, but there's no reason you have to do it painfully, card by card
The flipped back is often a Vehicle that is automatically crewed on your turn, thanks to another new mechanic called Living Metal
As a result, having a few tricks is probably for the better
Angel of the Dire Hour Darkest Hour Finest Hour Gerrard's Hourglass Pendant Hour of Defeat Hour of Devastation Hour of Eternity Hour of Glory Hour of Need Hour of Promise Hour of Reckoning Hour of Revelation Hour of Victory Hourglass of the Lost Infinite Hourglass Lost Hours Ninja of the Deep Hours Predators' Hour Sage of Hours Sword of Hours The Eleventh Hour The Hourglass Coven Watcher of Hours
And that's before we even go looking for cards that break it like the nameless Elvish Archdruid or Gilt-Leaf Archdruid
In general, when looking at power level, I considered the overall game plan, the synergy of the 99 with that game plan, things like interaction, ramp, mana base and card draw, the commander, and the power of the remaining stand-alone cards