How about a new card type like Events that change how certain things work such as:
Global Warming 3R
Event
(Events cannot be countered)
Global Warming can only be played if there are 4 or more mountians in play
all plains become islands
all forest become swamps
any player may play BBBB or UUUU to destroy Cardname "screw the environment, I'm cold NOW!" - Drew Carey
or maybe:
World War 3RG
Event (Events cannot be countered)
All Players may declare attackers during any opponent's attack phase
If 5 or more creatures enter the graveyard during one turn, Destroy World War
or
Feast for Enemies 3W
Event (events cannot be countered)
Green Creatures gain protection from blue and black
Blue Creatures gain protection from red and green
Red Creatures gain protection from blue and white
White Creatures gain protection from black and red
Black Creatures gain protection from white and green
If there are more than 4 creatures of one color in play, destroy Cardname
I know they're very much like enchantments, but I could see some type of variation of this...
Global Warming 3R
Event
(Events cannot be countered)
Global Warming can only be played if there are 4 or more mountians in play
all plains become islands
all forest become swamps
any player may play BBBB or UUUU to destroy Cardname
"screw the environment, I'm cold NOW!" - Drew Carey
or maybe:
World War 3RG
Event
(Events cannot be countered)
All Players may declare attackers during any opponent's attack phase
If 5 or more creatures enter the graveyard during one turn, Destroy World War
or
Feast for Enemies 3W
Event
(events cannot be countered)
Green Creatures gain protection from blue and black
Blue Creatures gain protection from red and green
Red Creatures gain protection from blue and white
White Creatures gain protection from black and red
Black Creatures gain protection from white and green
If there are more than 4 creatures of one color in play, destroy Cardname
I know they're very much like enchantments, but I could see some type of variation of this...