A creature with protection from one or more colors of magic cannot be affected by any magic of those colors. For example, a creature with protection from blue cannot be blocked by blue creatures, dealt damage by blue creatures, or enchanted, damaged, or otherwise affected by blue cards.
One thing that was not uncommon to see people debate about was the interaction between Black Knight and Balance. It was fairly consensual that you really didn't have to sacrifice a Black Knight to the Balance, as it couldn't be affected by white cards, but there were deeper implications. If your opponent has a Serra Angel and you have a Sengir Vampire and a Black Knight, do you have to sacrifice the Vampire? Should you even count the Black Knight, i.e. could you keep both your creatures? Protection was going deep, which makes this card possibly the first ever "un-card":
|"Cannot be [...] enchanted" is actually right there in the rulebook :)|
I could go on about amusing alpha cards, but I think I'll end for now with a quote from Magic Lampoon; on the original text for Living Lands: Some cards [...] make reference to something from real life. “Enchanted, killed and so forth” was an amusing homage to the way that Arnold Schwarzenegger is known for speaking. Yep.
Anyway, I found another pair of cards from ABU that seem to be cut from the same frame. Apart from cards with a common backdrop (like Healing Salve, Disrupting Sceptre and Berserk), we seem to have an interaction between Guardian Angel and Paralyze.
|Also, probably easier to find these two in a mid 90's collection than a Mox Jet and a Forcefield.|