Grinding Metal Slimes is one of the fastest ways to get EXP. They give some of the highest EXP of any monster but can be difficult to defeat without preparation and strategy.

Some tips for defeating metal slimes:

1. Use the ability Metal Slash: Metal Slash can be unlocked by Hero, Hendrick, Erick, and Sylvando. It costs 12 points in the Sword skill tree and does 2 damage to metal slimes.
2. Have your attackers equipped with Dual Wielding: Dual Wielding allows you to hit twice per attack.
3. Use abilities that deal critical damage: Critical damage will instantly Metal Slimes so abilities such as Critical Claim, Thunder Thrust, and Hatchet Man will be helpful.

Here is a list of types of Metal Slimes, the experience they give, and where to find them:

Act 1:

Slime Type	Sprite	Experience	Locations
Metal Slime		2,010	Gallopolis Region, Dundrasil Region, Ruins of Dundrasil, Caverns under Octagonia, Insula Orientalis
Liquid Metal Slime		10,050	The Other Side, Insula Orientalis, The Royal Library, The First Forest

Act 2:

Slime Type	Sprite	Experience	Locations
Vicious Metal Slime		12,100	Heliodor Region, Heliodoran Foothills, The Emerald Coast, Heliodor Sewers, The Kingsbarrow, Insula Orientalis
Hardy Hand		34,400	Laguna di Gondolia, Mount Huji, The Manglegrove – Whale Way Station
Metal King Slime		70,070	Fortress of Fear
Vicious Liquid Metal Slime		30,300	Dundrasil Region, Ruins of Dundrasil, Caverns under Octagonia, The Battleground, Insula Orientalis

Act 3:

Slime Type	Sprite	Experience	Locations
Metal Slime		2,010	Insula Orientalis, The Champs Sauvage (North)
Vicious Metal Slime		12,100	Insula Orientalis, The Champs Sauvage (North)
Vicious Liquid Metal Slime		30,300	The Disciple’s Trial – The Cruel Crypt
Hardy Hand		34,400	Mount Huji, The Champs Sauvage (North), The Manglegrove – Whale Way Station
Metal King Slime		70,070	The Battleground
Vicious Hardy Hand		91,020	The Sage’s Trial – The Fierce Forest
Vicious Metal King Slime		161,610	The Luminary’s Trial – Citadel of Spite

The Hallelujah/Electro Light Strategy

This is one of the most efficient methods, potentially gaining you up to 1,000,000 EXP per run. It consists of using the pep powers Hallelujah, that increases EXP gained, and Electro Light, which forcibly spawns Metal Slimes.

The requirements for this method are the following:

1. Having all the party unlocked (except Hendrick): This is necessary to be able to use Pep Powers.
2. Having the ability Pep Up: This will get Pep Up on Hero so we can use the Pep Powers. You can get this ability in the Luminary part of the skill tree.
3. Having the ability Critical Claim: This will allow Erick to instantly kill metal slimes. You can find this power in the Guile part of the skill tree.
4. Having the Pep Power Dirge of Dundrasil unlocked: This will allow you to put metal slimes to sleep, preventing them from fleeing. It’s unlocked once Rab and Hero unlock the Kasnooze ability. Hero needs to be at level 35 and Rab needs to be at level 32.

Some alternative recommendations:

1. Having Thunder Thrust unlocked: Serena and Jade can learn it in the Spears part of the skill tree. This ability can instantly kill metal slimes but also has a high chance of missing.
2. Having Hatchet Man unlocked: Hendrick can learn this ability in the Axes part of the skill tree. It works the same way as Thunder Thrust.
3. Increasing the chances of getting Pepped Up: You can do this by filling the skill trees. It will help speed up this strategy.

Implementing the Strategy

First, have Sylvando, Hero, Jade, and Erick in the lead party. Find any weak enemy and start a battle with it. Set Battle Speed to Ultra-Fast to speed things up.

Kill all but one enemy, then have the hero use Pep Up and switch him out for Rab. Then use Defend on each party member under they’re all pepped up.

Tip: Use Accelerate with Sylvando to make the fight faster.

When a character gets pepped up, put them in the standby team so they doesn’t lose their pep status.

Once you have Erick, Hero, and Jade pepped up, put them in the main party and use the Pep Power Hallelujah to get more EXP.

Once done, put Rab, Hero, Jade, and Sylvando in the main party and repeat the process. When these four get pepped up, put them all in the front and defend for one turn.

At this point, use the Pep Power Electro Light to force metal slimes into the battle. Then change the line-up by replacing Sylvando with Erick.

Have Rab use the Pep Power Dirge of Dundrasil to put all metal slimes to sleep and prevent them from running away.

Finally, move all characters that have critical skills to the main party and use them until the metal slimes are defeated, gaining you massive amounts of EXP.