Combined with Scute Swarm or Scapeshift, you can quickly get a major board advantage in terms of both creatures and mana, which makes you nearly unstoppable if you can add card draw
Jumbo Cactuar combos can one-shot players across different formats
The goal is to get a few counters in play, then proliferate them and increase them
The real draw is that Shanid triggers off playing legendary lands, providing card advantage for very little opportunity cost
Advanced Search Sets Random Syntax Abian, Luvion Usurper (playtest) Academy Elite Aeon Chronicler Aladdin's Lamp Alandra, Sky Dreamer All-Fates Scroll All-Seeing Arbiter Alquist Proft, Master Sleuth Altar of the Wretched Ancestral Anger Arcanis, the Omnipotent Avatar Azor, the Lawbringer B.O.B
Eventually, the cost was high enough that the team felt it was just neater as a double Time Walk