Aang's Iceberg Versatility is the name of the game for this enchantment, as it can be used either to earn an extra enters-the-battlefield trigger for one of your permanents, or to lock out an opposing permanent for as long as you need to in order to win the game
While you get one use out of regular schemes, ongoing schemes stay active until they get abandoned once set in motion
They're fairly useless on their own, but assemble all three and you get a whopping seven mana from just three lands
Should You Buy Boosters or Singles
This ability not only lets you slowly take down your opponents strongest blockers, but it also works incredibly well with other decks like Yawgmoth, Thran Physician, which also spreads -1/-1 counters around for your benefit
Having that extra bit of speed for every single deck type in the game can be surprisingly powerful, as it can essentially put the player one turn ahead of their opponent in terms of resources