As long as the top card of your library is a land card, this creature has ": Add two mana of any one color." As long as the top card of your library is a creature card, this creature gets +3/+3
Then, you can tap it to put a Burden counter on it and draw cards equal to the number of Burden counters on it, but at the beginning or your upkeep, you lose life equal to the number of Burden counters on it
While seemingly simple nowadays, what Gary did was groundbreaking at the time, and it sold the public on drafting at a time when the world mostly considered Constructed to be king
More specific pieces can be found in the last part of this article
These Tag Team Pokemon are some of the strongest cards in the set
Especially because its very likely that you arent wealthy enough to have one in your deck too