This is different than how the mana value of other double-faced cards is determined
This card is likely better than it looks
There are other cards in this space which Ill let the Reef stand in for, as they arent exactly card draw, like The Fourth Doctor and Korlessa, Scale Singer, but nothing is as good as the Reef
Brotherhood of the Fire Fist - Bear English - Near Mint - 1st Edition Product Details Number : FIGA-EN023 Rarity : Super Rare Attribute : FIRE Monster Type : Beast-Warrior Card Type : Effect Monster Attack : 1600 Defense : 1200 Description : Once per turn, when this card inflicts battle damage to your opponent: You can Set 1 "Fire Formation" Spell Card directly from your Deck

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Based on the latest market prices tracked on TCG Stacked, a foil copy of Entomb is worth about $95.16 USD