In practical terms, it's not really necessary for a color to be represented in a given format all that much - especially in older formats from when design was more primitive - but the idea is that it doesn't make any sense for a given color (or set of colors) to be consistently better than the others because you're just marginalizing a certain style of player for no real reason
This is a very flexible ability, but it works particularly well with a board full of Saprolings, doubling it into a massive horde which, if left unchecked, will continue to double turn on turn, until it consumes the entire pod
Drop this on turn one to cast a three-drop early and set a pace your opponents cant match
This thing is pretty nasty in most landfall decks and was just printed last year
Entering tapped is a downside, but the momentary loss of tempo is often worth it in the long run
The borderless foil version of Tiamat retained its value at around $50, but its other variants are much lower in price