Umaro's Cave is a short but intense dungeon area. Like many World of Ruin areas, there is a Status theme in this dungeon, and that theme is Imp. Almost every Monster found here will inflict Imp in one way or another. As usual, Status-protecting Relics such as Ribbons and White Capes are useful here.
Encounters in Umaro's Cave
There are two different sets of Encounters. In the room you start in as well as the lower Basement, you will rarely run into a Pug, better known to Final Fantasy veterans as a Tonberry. These weird-looking little guys are far tougher than they look, sporting 8,000 HP and high Mag.Def. They will use Step Mine every round, which may be anywhere from dangerous to downright deadly depending on how you play the game, but that's not the bad news. The bad news is they use Step Mine as a guaranteed counter to any attack, right after they hit you with the devastating Cleaver special. Essentially, you either need to use incredibly powerful attacks like Bum Rush, or find an alternate way to deal with them. They are vulnerable to a variety of Statuses, so why not turn the dungeon theme on them and cast Imp? They will deal critical damage in Imp form, but that's a whole lot less damage than they're doing otherwise. If you do choose to use Magic, focus on their weaknesses to Fire and Thunder.
Poppers appear in groups of four and can use Tail to cause Imp or Stone to cause Muddled. If the targeted character happens to be level 33, Stone will likely kill them ouright. Fortunately, Poppers have relatively low HP and are weak against Fire. They sometimes appear alongside Kiwoks, who also have an Imp special (Pick) but are vulnerable to Ice and have double the HP of Poppers.
Like the Orogs and PowerDemons of Darill's Tomb, the Kiwoks and Ceritopses drop the Relic (a White Cape) that protects against this dungeon's common Status ailment. They also sometimes appear together. Ceritopses are similar to Kiwoks except that they have better defense and are vulnerable to Fire instead of Ice. Their Imp special is Pal Maker, and they can use it every round instead of only every other round.
The Encounters in the other areas of Umaro's Cave also feature Ceritopses, both in trios and accompanied by pairs of Tomb Thumbs. These tiny human soldiers do not normally inflict Imp. Their gimmick is using Dash to Haste themselves. However, if you leave a single Tomb Thumb alone on the battlefield, it will use Imp Song to try to turn the entire party into Imps. Thunder and Water attacks work best on them.
Finally, there are Anemones, which appear either in groups of four or in groups of two accompanied by a Tomb Thumb. They don't attack directly, relying only on the Imp Touch special (which predictably causes Imp). They will counter attacks by using Mega Volt on themselves to heal slightly, due to their ability to absorb Thunder. If left alone, they will start attacking with a powerful Giga Volt. They are weak against Fire, but since they don't share a weakness with Tomb Thumbs, defeating the group without leaving any of them alone can be tricky. You'll generally want to defeat the Tomb Thumb first, then defeat both Anemones simultaneously.
Trying to keep up with the Pugs' damage can be frustrating. A better idea is to use the Vanish Spell or Phantom summon to make your party immune to the Pugs' attacks with Clear. As long as you don't trigger a Pearl counterattack, you should have no problems.
Navigating Umaro's Cave
This is a small area with a lot of pit traps and odd connections.There are three doorways in the Basement 1 South where you start. All three connect to different parts of Basement 1 North. The two darkened bits of floor near the western doorway are pit traps, and there's another pit trap on the path through the eastern doorway. There are chests through both the western and central doorways, but the path connecting them is also a pit trap. Every pit trap deposits you to a different part of Umaro's Cave Basement 2.
The most dangerous battle here is contained within the chest on the other side of the western doorway. When you open it, you'll be attacked by three Pugs, which are different than the Pug enemies you may encounter normally. They will make a powerful basic attack and step forward each round. After taking eight steps forward, they will use Knife to almost certainly finish someone off, then start over. Each time you hit one Pugs with Fight twice, they'll take a step back. They will counter Magic with Pearl, but fortunately they lack Mag.Pwr so the damage is not severe. They're weak against Fire. The main issue is that they have 14,001 HP each, so defeating them with just Fight is not terribly practical. If there was ever a time to use Vanish (or summon Phantom), this is it. It will nullify all of their attacks unless you trigger a Magic counterattack.
If you survive the Pugs, you may win the Minerva, a powerful Armor for Terra or Celes. Leave through the doorway you entered with, then avoid the pit traps again and head to the central doorway to retrieve the contents of the second chest, an X-Ether. Head down to Umaro's Cave Basement 2 via any pit trap or even the stairs at the north end of Basement 1 North. You'll see a wooden walkway connecting raised platforms. There's a chest containing a Gauntlet at the southwest end of this network.The central stairs lead back up to Basement 1 North, but if you take the long bridge on the east side you'll end up in a small new area with another bridge and two switches. Both switches open pit traps beneath your feet, but the one to the east drops you into Umaro's Lair.
If you examine the bone carving here, you will obtain the Terrato Esper, but Umaro will attack. You can also walk right by it and take the stairs to exit back to Narshe. You'll have to defeat Umaro before he'll join the party (or let you leave).
Umaro
Umaro's basic attacks are nothing compared to the Pugs. Even the triple-damage Tackle should be survivable with little problem. Umaro's Blizzard Ability is likewise rather weak. Where Umaro becomes dangerous is deep within his battle scripts.
Umaro has several different counter abilities. He won't directly counter Magic, but after casting three Spells on him, he'll use a Jump attack. He can counter other attacks with Tackle, unless those attacks are Fire-Elemental, in which case he can also counter with Blizzard.
After you've dealt at least 6,960 damage to Umaro, he'll use a Green Cherry to power himself up. Despite the message about "Power 100 times up!" this does not increase the damage of his attacks. Rather, it gives him the Safe, Shell, and Haste Statuses. In addition to this general power up, Umaro will periodically make a more powerful attack using Snowball, Surge, or Lode Stone. Keep up the pressure, exploiting his weaknesses to Fire and Poison, and soon enough, Umaro will fall.
After he is defeated, Umaro will stay in the room. If you speak to him with Mog in the party, he will join your cause. (If Mog isn't currently with you, but you don't want to fight your way back here, the Moogle Charm will help get him there safely.) Umaro is essentially a berserker, and you can change his Relics but not his Weapon or Armor, nor can you assign him an Esper. He's a fun character to mess with, especially when you find his unique Rage Ring and Blizzard Orb Relics, but hard to make truly effective since you can't control him. His inability to take advantage of Esper level up bonuses is also a major flaw in the long run.