First, they boosted the power and toughness bonus it granted, then dropped the cost to only one mana to cast and equip, and finally made it so it gave the creature 1 toughness, and it ended up being that fateful 1 that made Skullclamp into a monster, since all you had to do was play one-toughness creatures and you suddenly had a repeatable, colorless, one-mana Divination
It then becomes Bloodsworn Knight , a card that has power and toughness equal to the number of creature cards in your graveyard
If your opponents cant deal damage to you consistently, this thing turns into an Angel factoryand those 4/4 fliers close games fast
I mean, have you ever seen how often these cards are used in older formats
It turns out that forcing opponents to resolve your ETB triggers can lead to some very fast and unpleasant kills