Risk Factor is absolutely good enough to deserve this slot on my Top 20 list, which is really saying something for all of the other good cards that have come before it
Cat Teferi Combo Produce 1 mana from "Mox Amber" or "Mox Opal", bounce it with "Teferi, Time Raveler" and draw a card, cast the recovered Mox and blink Teferi, and if you repeat the process of bouncing the Mox with Teferi again, you get infinite mana and infinite card draw
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It also creates a resource advantage by forcing the opponent to trash a card from the hand
It doesnt fix your mana, unlike Cultivate or Reach, by fetching any basic land, and that drops it on this list to the 10 spot