I had a deck many years ago that was blue/white and used a blue enchantment that made players pay 2 colorless to attack. I can't remember the name of the card, but it was around Mirage, no later than Urza block. I also had Kjeldoran Outpost and Thawing Glaciers.
The main concept of the deck was to get out the mana generating diamonds from mirage, then blow away the lands with Armageddon and keep the opponent locked out of attacking for a while.
This card is stuck in my head and I can't seem to find the name of it anywhere. I remember seeing it reprinted as a white enchantment sometime ago as well.
If anyone knows what this card might be, please let me know the name. I have not found anything via searching so far.