mtg cards with x Mana Cost: humanReadable.=[XR], 52 put a +1/+1 counter on that creature and a +1/+1 counter on X Set X to specific value

That's a powerful synergy and a brand-new card that has a brand new ability for a reasonable three mana that fits into any deck

There are plenty of other reasons, and I could go on and on

Tezzeret the Seeker I remember Tezzeret the Seeker being a much more ubiquitous card than it is now, but I dont think its ever stopped being good

$0.59 Polluted Mire Urza's Saga $0.35 Drifting Meadow Urza's Saga $6.99 Privileged Position (Borderless) Double Masters 2022 Variants $0.49 Slith Predator Mirrodin $3.99 Land Grant Mercadian Masques $10.99 Noxious Revival New Phyrexia $0.35 Disciple of Law Urza's Saga $0.35 Slippery Karst Urza's Saga $0.39 Gilded Light Scourge $9.99 Force Bubble Scourge $0.35 Expunge Urza's Saga $0.79 Rapid Decay Urza's Destiny 0 results found

During regular combat damage, the 2/2 creature deals 2 additional damage to the 3/3 creature