6. Unlocking Grand Trine - Final Fantasy VI
Despite looking like he's borrowed his trousers from Krusty The Klown, Strago the Blue Mage from Final Fantasy VI is no joke whatsoever, for if you follow this distinguished gentleman's side-quest you'll unlock one of the most powerful spells in the game, and trust me it's hard to make fun of someones clothing choices when you're being disintegrated into atoms.
Getting Strago to join the party is itself an optional side mission, requiring the player to enter the Cultist's Tower in the World Of Ruin with Relm in your party, upon which she will make Strago see the error of his ways and him vow to put things right.
And by "right" we mean use his blue magic to steal enemy attacks and utterly embarrass them.
If you happen to have Strago and Relm in your party when you visit Thamasa, you'll unlock his personal side quest, in which he learns that a monster that he hunted as a youth but could not defeat has been spotted again.
With the fire stoked within him once more, he vows to slay the beast for good, and in battle, he'll be able to learn Grand Trine, a move that sits on par with the Ultima spell in terms of raw power.
And when you remember that Ultima is basically like shoving your enemy's faces into a microwave and hitting the nuke button, it makes Grand Trine well worth learning, plus it costs less MP! bonus!