At the time Timetwister was released, you could play the Mox artifacts, zero mana artifacts that provide mana
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Also, basic land cards had been removed from core set booster packs for a while, so these Starter Decks were the only place to get the new Ice Age art lands
And lastly, another important aspect to highlight about Sky Seal Stone is that it is the perfect companion for Drapion V
SR Super Rare Fish Sonar X SPELL Add 1 Level 7 or lower monster from your Deck to your hand, that mentions "Umi", or is a WATER Normal Monster, then if "Umi" is on the field, you can Special Summon 1 WATER Normal Monster from your Deck
This turns BLS into a board wipe that also deals some serious damage to your opponent its easy to see why BLS is such a game winner in Goat format, and why Chaos decks are such a popular choice