I begin the "post game" content of the game and take on the Kraken.
Here's where you can find the Elemental Rings. Always prioritize stealing over farming drops because you can often bring 99 of the common drop and guarantee the rare drop with enough attempts. I also recommend replaying pickpocket to save time. Replaying Extension Pickpocket against large groups of enemies can also save time. If a drop is your only option, absolutely kill the enemy with the Lucky Hand summon.
*Earth Ring- Pickpocket Chimera Geo from the Dissection Facility. Bring 99 Potion Berries. They also drop them rarely.
Water Ring- Pickpocket Chimera Muse from the Dissection Facility. Bring 99 Potion Berries. They also drop them rarely.
Wind Ring- Pickpocket Chimera Wings at the Dissection Facility. Bring 99 Potion Berries. They also drop them rarely.
*Fire Ring- Pickpocket Chimera Frays at the Dissection Facility. Bring 99 Potion Berries. They also drop them rarely.
Thunder Ring- Pickpocket Barbarossas from either Fila Del Fia or the Caging Tower. Bring 99 Potion Berries. They do drop them rarely. Thunderdrakes also have them as a rare steal with higher percentage and the potion berry common steal, but they show up in much smaller numbers so I think it's faster to go with Barbarossas.
*Ice Rings- A rare drop from Sun Flayers in Nightmare castle. You cannot steal these from any enemy in the game. They also drop from Capricorns, a sandcraft enemy around the and circling Yggdrasil. Capricorns are much easier to encounter, but you can't use Lucky Hand. Pick your poison here. You may just want to sell the one you win from Lolithia at the black market and just buying three more of them, four if you want one to mystic. If you're going to skip one, this would be the one to skip.
Dark Ring- Pickpocket Evil Dead from Dim Root Path. Bring 99 Potion Berries. They also drop them rarely.
Light Ring- Pickpocket Fairy Light from Glimmering Emerald. Bring 99 Potion Berries. The steal rate is only 3% so make use of Replaying Extension Pickpocket on groups of Fairylights. They also drop them rarely.
*The Cradle of the Medal Gods is a great place to get Fire and Ice rings, but it is a one time only area. Fleuretys drop ice rings and come in large groups. Haborins drop fire rings and also come in large groups. Earth rings drop and can be stolen from Sekmets. Their common steal is a potion berry. If you plan on completing the Abyss, I highly recommend at least getting four ice rings at the Cradle of the Medal Gods before completing it. Fire and Earth rings aren't too difficult to acquire elsewhere, but you'll most likely get four Fire and Earth rings in the process.
You'll also need the following status protection gears for a leveling trick.
2 Moonstones, 2 Hazel Springs, 3 Blue Bracers, 3 Clear Chimes, 3 Memo Pens, 3 Heart Leafs, and 2 Alarm Clocks. Most of these can be stolen easily enough. Keep in mind, this assumes you have the Full Libra for one of your characters for total status immunity. Amulets are not good substitutes for the leveling trick.
Moonstone- Pickpocket Rat Monkeys from the Decaying Labrynth. It's actually their common steal. Bring 99 Mini Carrots.
Hazel Spring- Pickpocket Gagisons from Ka Dingel. Bring 99 Potion Berries.
Blue Bracers- Pickpocket Oaks from the area around Little Twister or from Lunatic Garden. Bring 99 Pixie Dust.
Clear Chime- Pickpocket Myconid from the Ruin of Dreams. Bring 99 Pinwheels.
Memo Pen- Pickpocket Rock Buster from the area north of Boot Hill. You must teleport to Boot Hill and take the sandcraft to the nearby beach, north of Boot Hill. Bring 99 Potion Berries. Alternatively, steal from Marids at the Lunatic Garden. It's a common steal, but their rare steal is a Water Ring and getting 99 of them is not reasonable.
Heart Leaf- Pickpocket Saracenians around the Secret Garden. Bring 99 Heal Berries. They also drop them rarely.
Alarm Clock- Pickpocket Mushussu from Nidhogg Pass. Bring 99 Potion Berries. They also drop them rarely. Alternatively, you can steal both Heart Leafs and Alarm Clocks from Buckbairds at the Demondor Pillar. Hearts Leafs are the common steal while Alarm Clocks are the rare steal. Obviously, getting 99 of either is not reasonable.