It's also important to consider what you're trying to ramp into
While I personally think that Exocrine s ability to clear the board and possibly even finish off opponents if life totals are low enough pushes it over the top, there are a variety of useful effects to be found among these creatures
If the copied creature card has X in its mana cost, X is considered to be 0
Pair Yawgmoths Will with a few cards that pump out mana, like Dark Ritual, Lions Eye Diamond, or Cabal Ritual, you can build a high storm count and then win off the back of a Tendrils of Agony
Lands That Tap for Color When creating your manabase, your first priority should be to make sure you have your colors
Vindicate will destroy any permanent including lands, but it's sorcery speed