Ancient Silverback

Six mana for a 6/5 was already past the curve for a vanilla beater the year this came out, so the green mana sink is what justifies the cost: pour mana in and the body simply refuses to die. Regeneration was green and black's structural answer to the era's removal suite, and Urza's-block creatures leaned hard on it because the format was dense with combat tricks and spot removal that destroyed rather than exiled or bounced. The shield turns every block into a question the opponent has to outspend rather than out-trick: kill it once and another green mana brings it back, tapped and healed, ready to come back the next turn. That repeatability is the whole design. It is not a card that ambushes you; it is a card that grinds, daring the other side to find an answer that sidesteps destruction entirely (exile, sacrifice effects, bounce) rather than burning resources on a creature that keeps standing up. The rate looks fat by modern standards, but it sits at the tail end of an aesthetic Wizards has since largely retired: the big, mana-hungry green fatty whose toughness lives in an activated ability instead of the printed number. Read it as a snapshot of how green protected its top-end before indestructible and hexproof became the keywords of choice.