Magic 2010 (M10)
Whether a part of control, aggro, tempo, or combo decks, Brainstorm was an absolutely defining force in Vintage until its eventual restriction, and to this day, is clearly way, way over the line for Legacy, except that it just gets a pass, because we want it
And while synergies are great for Magic , they dont work well for a Top 10 list
You may even consider some of blue's copy magic a form of tutor
The two Koths obviously want to be in the same deck as Mono-Red or two-color deck with enough basics to fetch out and enough duals to make the -3 work
Crucible of Worlds is a true multi-format all-star, showing up everywhere from Modern to Legacy and even Vintage