These are both white, with Attentive Skywarden and Seedpod Caretaker being able to transform your incubators without paying the two generic mana.
According to the lore text at the bottom of the card, the creatures are trapped on a rock (possibly an asteroid.) Someone left behind an encrypted log recording the existence of slivers, either an unlucky explorer or, perhaps, a scientist involved in experimenting with the creatures, which would be a nice callback to the Riptide Project
4 Field Of The Dead Lost Its Counters The Land Field of the Dead proved to have a host of problems
If the creature Rancor would enchant is an illegal target by the time the spell tries to resolve, it doesn't resolve
The enters-the-battlefield ability, on the other hand, is completely inspiring since it allows you to ramp by putting the best land out of the top five cards of your library onto the battlefield
R&D management liked the idea of "Stepping Stone Games" but chose to pursue other things at the fair