That's when you need skilled help, of a kind that only a certain type of individual can provide. Karn is that individual, and he can provide that service...for a price.
Here's what the manual tells us about Karn:
"During the course of your adventure, Karn will learn to meld together with other members of your party and become a force to be reckoned with. "
"Use Karn's magic of transformation to meld with other warriors."
I hate that one of the few black characters in video games was changed to another generic white dude, and I also hate that his initial depiction is so close to a stereotype. I won't apologize for it on behalf of Capcom, but I will say that I wish they had tried a little harder to give people a decent representation of a black character.
The issues of Japanese games and black characters is a whole series of articles in and of itself, so I'll stop here.
Getting back to Karn, he is the party thief, and as such is typically the fastest member of the party (behind Nina when she is casting that is), though one of the weakest in terms of durability. He doesn't learn any magic, and doesn't have any obvious uses on the main map screen.
Until you find a locked door or chest.
Placing Karn in the lead allows him to pick locks and get access to areas that you usually can't. It's a mechanic that is necessary to advance the plot, and to find some rare items in the dungeons that you explore after finding him.
Karn also has a secret, and it's a good one. He can fuse with three of the party members to create special characters that have their own unique uses.
Combining Karn with Bo and Gobi gives you Shin, who shares Bo's field abilities and gains an improved HP pool. He's basically Bo 2.0, with some extra tricks, but comes at the expense of three party members.
Fusing with Gobi and Ox gives you Debo, who is only usable underwater, due to Gobi being the dominant form here. Kind of a useless transformation given the low number of underwater maps you explore in the game. Debo is also the only one without a field ability. Lame.
Fusing with Ox and Bo grants Doof, arguably the strongest character in the game, who has the special ability to move enormous weights, and to hit like a mac truck in battle.
Finally combining with Ox, Bo and Gobi creates Puka, who is basically a tiny green screaming ball of platypus death. He has the ability to shout open dragon doors that are scattered around the world and in certain dungeons, and has the ability to cap his damage, although it means only having one character in reserve. His duck bill belies his fearsome nature, trust me.
Many people find Karn one of the best characters in the game only because of his fusions, but he can hold his own very well in his normal state. His speed combined with his many elemental daggers give him a very versatile role in battle. He can freely switch weapons in battle and act as a change up against random mobs with elemental weakness, all without having to waste precious AP that could better be used for boss fights. Tag him in when you need a quick elemental stab or two.
He can act as DPS, elemental DPS, or even a support healer with item use. Of course, his lack of ranged weapons makes his low defense exploitable if you plan on maximizing his damage output by placing him in the front row, but those tactics will be explored at length in some of my videos later on.
Karn is a fun character with a lot of baggage, both in game and out, but he is well worth the risk of bringing along.
If you still find yourself in need of a certain kind of help, check back next time to learn about Gobi, the shadiest merchant to sail the seas.
See you then and thanks for reading.