The various frog creatures all play around the idea of hopping in and out of play, triggering both ETBs on that creature and many secondary effects on your support cards
If you give a creature vigilance twice, this doesnt make any difference
If you dont need to hit anything, you can always hit your opponent directly for some early damage
Essentially, The Soul Stone is two excellent cards rolled into one, and that's why it's going to be a hard-to-find staple of black EDH decks
The usual light blue color palette still shines through in the right light, but the variety of other colors on the holofoil makes Glaceon's simple design pop
A lot of the best commons in the set happen to be adventures, and there are bomb rares like Horn of Valhalla, Illithid Harvester, and Altar of Bhaal with the mechanic