It just uses the word, "Swamp." Another good example is extort, which has the Black and White symbols in the reminder text, or a fetchland like Mountain Valley that clearly is Red and Green in flavor and mechanically, but is allowed in decks without Red or Green
This even includes a powerful Reserved List card printed 26 years ago that could easily be a Brawl all-star
The Thundertrap Trainer looks at an extra card, can hit any noncreature and has kicker, while only losing a point of toughness in return
Caring about creature tokens and not spell-slinging, Hildibrand is a mildly interesting card on its own, but very out of place in this precon
If you descended this turn, you may choose both instead
Then you spend three mana, two Phyrexian white so that could be 1 and 4 life or 2 and 2, and then sacrifice two artifacts, to place an indestructible counter here