95% of the time, the triggered ability probably isnt worth a removal spell thats going to be better sent towards Rhystic Study or Smothering Tithe, but once enough cards have been exiled, the risk from rolling a 20 is going to weigh on your opponents
Killing an opponent's Seer allows you to draw a card, sure, but by then your opponent has already taken the best card out of your hand, so youll have to evoke that Thoughtseize bug to draw something good enough to replace it
It draws a given number, in this case four for five mana, one more mana and card than Harmonize, Concentrate or Ambition's Cost
Cast any of those token-generating spells, and Rapid Augmenter gets a huge power boost in the form of +1/+1 counters and becomes unblockable
And Then Along Came Zeus gives you the option to do five damage to a character or location, giving you flexibility when dealing with lore threats on your opponents board