Found across all rarities, some are certainly better than others so lets take a look at all the prototype cards and see which is the best
Mixing Emerald and Amber can lead to a pretty nasty deck
(2024-01-12) After you draw a card as Nicol Bolas's first loyalty ability resolves, the next opponent in turn order (or, if it's somehow an opponent's turn, that opponent) chooses a permanent they control or chooses a card in hand without revealing that card
The fact that he boosts your Saprolings alone is enough to slot in a few of the cross-type synergy cards, like the two Nematas, and also some more general Saproling generators, like Fungal Sprouting
Lets look at what some of your strongest card interactions are and how you can use them to dominate the board
Play Boosters and Collector Boosters provide deeper dives into Foundations