(And, of course, the sweet spot is when you have very strong tribal rewards and very strong individual creatures!) Sometimes you might have to play a couple creatures that are just below the bar of normal playability, but you certainly don't want to fill your deck up with those
In Commander, there are some quick ways to mill your entire deck to make Thassas Oracle win you the game immediately
The real backbone for this deck, however, comes from Lorwyn Eclipsed
When you search your library this way, put a +1/+1 counter on target creature you control
For the flip you get two casts of something like a Mana Leak but making your opponent pay 2 instead of 3
Although you'd probably want common Cultivate there instead and save your 5 Uncommon slots