So long as silver borders were the mark of Un-set cards, mixing legality within a set remained a technical roadblock
Context: Kai's High Tide deck was better than average, but the strategy was known
This is limited because it only hits other fliers, but you can cheat it out, get a really big Flying Creature with Lifelink, and protect your Flying guys
Wildcards don't care about sets, formats, or any other restrictionsif the Wildcard is the right rarity, you can craft it
Their playability is also not in question
Well, despite the fact that you can get away with not including them at a more casual table or in a deck with only one or two colors theres no denying their efficacy once you start to edge more competitive, or fancy playing a four- or even five-color build