Boss Battle: Kraken

Warning: The process of reaching the Sunken Temple will cost you a minimum of 50,000 gil. Just FYI.

You’ll enter the Sunken Temple on the third floor, and from there can either go up or down. I highly recommend you go up first, as the fifth floor is home to the Mermaids and thus devoid of enemies. There’s also a good deal of treasure, including a full set of diamond armor that’ll make you smile if you’ve got a warrior along. I didn’t, so the whole set was useless to me and I did not smile.

Backtrack to the third floor and continue down. You’ll find the Kraken on the fifth floor, which seems to be the standard floor for boss battles in FF1. I recommend healing as close to full health as possible before battle begins.

The Kraken is ugly and he hits like a truck. I highly recommend casting Shield II and Invisibility II at the onset of battle, if possible. That aside, cast Haste and Saber (or use the Giant’s Gauntlets to get the Saber effect) on your primary physical attackers and go to work. It's sort of a race to see which of you can deal out damage faster, but with Shield II and a decent amount of HP you should come out on top.