Certainly the difference in mana cost is huge, but Squall does a great job with the right support pieces
Unless youve delved deep into the late-game, that four mana is likely to be a huge stumbling block, removing an opponents threat before it ever hits the field
You can target an untapped permanent for untapping, but no cards you have that say when a permanent you control becomes untapped would trigger
But seriously, its one of the best green win conditions in EDH, and for a quarter, you cant get much more bang for your buck
This includes , and Ice Age/Alliances , Mirage/Visions/Weatherlight , Tempest/Stronghold/Exodus , Urza's Saga/Urza's Legacy/Urza's Destiny , Mercadian Masques/Nemesis/Prophecy , Invasion/Planeshift/Apocalypse , Odyssey/Torment/Judgment , Onslaught/Legions/Scourge Mirrodin/Darksteel/Fifth Dawn and does not include base sets or pre-Ice Age sets