The most obvious of these factors is the synergy of haste with Saproling Burst, which was known to some as "The Fix." That extra turn almost doubled the strength of the Burst and made it hit for the full 20 damage in only two turns, which would normally mean a kill on turn five, or turn four if backed up by a Blastoderm
If you put an Aura on an opponent's permanent, you still control the Aura, and it still counts for your spells that have affinity for Auras
Sure, you can combo it with cards that put extra counters, but if you can dedicate that much resources to one card, you can dedicate those resources to other ones that win you the game on their own, rather than relying on a combination of cards
Is Force of Will Better Than Counterspell
Any rock that taps for two or more and either a Pili-pala or a Staff of domination, boom
Track your characters health with six themed damage dice and monitor your quest progress with the easy-to-read lore counter