MArcomage

This and all schools are just too expensive to make them worthwhile. They pull from the entire pool of cards (not just those in your deck) preventing you from screening (as you would by selecting the card for your deck). It's much cheaper to cycle cards than to play these. Their costs should be reduced or their effects improved to make them playable.

I agree on all counts.

+1

Each deck of mine who used such spells, gradually removed this type of summoning card over longer periods of testing.

Agreed.

Just pulling from your deck would make them too powerful as you could just include 1 card in your deck of that keyword and make that card a rare.

But having them pull non-commons would greatly increase their usefulness (esp the nature, which would have to have an increased cost).