Controlling the difficulty of a JRPG is important. You need mooks to be easier than bosses, you'd like the monsters to follow some sort of sorting algorithm of nastiness, getting tougher as the game goes on, and it'd be fairly ego-stroking if the super-secret hidden boss was incredibly challenging.

The annoying thing is that difficulty is not easily quantified for creatures in a JRPG game - and in particular, the statistics of a creature are not the primary determinant of difficulty. This can often lead to 'hard' bosses being surprisingly easy.

An example: In the game Lufia 2: Rise of the Sinistrals (Just 'Lufia' in Europe), there is a hidden boss that you can only fight quite near the end of the game - the Egg Dragon. This monster has 65535 HP and pretty good attack and defence statistics, along with no elemental weaknesses to exploit. It's also quite easy to beat.

Much earlier in the game - in about the fifth or sixth town you reach, if I remember correctly - the storyline boss is a giant spider. I generally consider this to be the hardest boss fight in the game.

Clearly these two are the wrong way around. Let's look closer to find out why.

The Egg Dragon has a number of actions it can take:
- A very strong physical attack against one member of your party. It won't quite kill your characters (Assuming they're at the maximum level and full health) in one hit, but on some of them it gets quite close.

- A spell that hits all members of your party for absolutely piddling damage (Omitted in the analysis for brevity - doesn't change much)

- A weak physical attack against all of your party, with a chance to confuse. (Omitted in the analysis for brevity - doesn't change much)

Each round, it acts before your characters.

Generally, the strategy to beat it goes something like this:
- One party member casts a healing spell on every character in the party. This spell will heal every member of your party to full health or nearby.
- If your designated healer is starting to run out of MP, one character uses an MP-recovering item on them
- The remaining characters attack

There are some further complexities involved - you need to deal with confusion if the Dragon uses that particular move, and there are some skills you can use to quickly chop off a lot of health near the start of the battle, but that's the simple form.

The tarantula boss, on the other hand, does a number of things:
- It starts with two allies, reasonably weak spider enemies.
- It can attack a single character for a pretty good amount of damage - probably three hits will kill any member of your party at this stage in the game
- It can attack all the members of your party (With a reasonably weak attack) with a chance of poisoning them
- It can attack all the members of your party (with a reasonably weak attack) with a chance of confusing them
- It can attack all the members of your party (with a reasonably weak attack) with a chance of putting them to sleep.
- It can summon new allies if you kill its old ones.
- It can heal itself by a little bit - it only starts doing this when seriously wounded

You only have three party members at this stage of the game, and the boss is weak to fire attacks.

Honestly, there probably isn't a general strategy for dealing with the Tarantula. By now I've come to deal with it by ensuring I pick up a powerful fire-elemental weapon before fighting it, and grinding a fair bit before taking it on. Any strategy would look something like this:
- Deal with whatever status effects the Tarantula has inflicted on you last round
- Heal wounded party members
- If one of your spellcasters is free, use a fire-element spell to damage all the enemies
- Attack the Tarantula

That's pretty general, considering how specific the Egg Dragon strategy was. A computer, even quite a dumb one, could beat the Egg Dragon. I'd be reasonably impressed with anyone who wrote an AI that could take on the Tarantula with a party of appropriate level - it's not a superhuman feat, but it wouldn't be easy, either.

So we've identified the key cause of the Tarantula being perceived as so much harder than the Egg Dragon - when battling the Egg Dragon, there's a simple set of steps you can follow every round that will guarantee you will win (The pattern is so regular that I could work out how many rounds it had taken me to beat the Dragon by counting how many MP-restoring items I had used). When battling the Tarantula, there is no formula - the strategy involved is very general, and heavily emphasises keeping yourself alive over doing damage. Pattern is the key - if you can slip into a pattern against a boss and still beat it, that boss is not very tough. You don't need to think at all - the symbols from the screen just get translated into button presses and fed back in. Against a tricky boss, each round is a life-or-death moment - you must carefully consider what the optimal strategy is.

But why could we slip into a pattern for the Dragon and not for the Tarantula? The Dragon has significantly better statistics. Indeed, with 65535 health, it takes more than half an hour to beat the thing. The Tarantula isn't nearly as threatening, from a pure statistics viewpoint - its attacks aren't as damaging and it isn't as durable.

If you look at the lists above, you'll notice that the primary difference is in the abilities of the creature concerned - the Dragon can basically only threaten the party with a very strong attack on one character (And the confusion, but in practice that's not a significant problem). The Tarantula, on the other hand, has allies, so it isn't outnumbered, it can inflict several status effects on multiple characters at once, and it can take advantage of 'free' turns by re-summoning its minions or even healing itself. It has more leeway to choose the optimal action. (Also, by the time you get to the Egg Dragon, you have much better healing magic, but that's an issue for a later article).

This is a very important insight - the actions that a creature can take are the primary determinants of its difficulty - not its statistics. It doesn't matter how much attack the creature has - if all it can do is attack, it will not be very hard to beat - excepting ridiculous cases, like monsters that can one-hit-kill every member of your party in one action. Depending on the way the game works, even that might not be a problem (Grandia 2 has some monsters that can cast a spell that does exactly that - it works because you can delay their actions by attacking them).

Hard creatures need to be able to disrupt the player's strategy, and they need to be able to take advantage of 'free' turns when the player isn't attacking them because they're busy dealing with whatever the creature did to them. They need to keep the player on their toes - every round, the player should be only two or three rounds away from a loss. The player should be on the defensive - their primary concern should be to stop their party falling apart around their ears, and any damage done is incidental. Such a setup also lets skilled players really shine, as it gives them opportunities to do some thinking and get a few more actions in, or make the ones they've got count more.

In general, 'hard' creatures should have the following abilities and properties:
- They should have allies. It's much easier to beat something when you can gang up on it - with allies, there are more creatures for the player to worry about, and some extra actions on the creature's side of the field.
- They should be 'fast'. This may mean something different in different battle systems. In Lufia, where battles proceed in a number of 'rounds', where each creature takes one action in speed order, it means going before the party. In a Final Fantasy, ATB style system, it means taking a number of actions - ideally, one action for every action the player takes.
- They should be able to cause status effects, preferably to several characters at once. Status effects disrupt the player's strategy, and are extremely annoying. However, if you only inflict one PC with whatever nasty you can cause, this is not necessarily a big deal - most games will allow players to cure a status effect in one round, so single-target status effects will only cause one lost action on the PCs part and probably won't stick around. Two or more, however...
- They should be able to heal themselves. Nothing says 'scary' more than the realisation that the boss can actually fix whatever you've been doing to it. It forces players to think - they need to be able to do damage to the creature faster than it can heal it off. It also punishes players for giving the creature free rounds - if round ends with the party worse of than at the start, then the monster is being difficult.
- It must be able to threaten the party. It's no good having allies, being fast, causing status effects, and being able to heal yourself if you can't actually hurt any PCs and get killed in one hit. The creature needs to be able to do significant damage to PCs, and it needs to be able to take a few hits in return.

Obviously, not all creatures should be like this - it's more a matter of slowly adding features from this sort of direction as monsters get 'harder', in addition to improving their stats so they can keep up with the party.

This is another aspect of the players-are-smart principle - they will find the quick and easy pattern to beating a given boss, and will then abuse it. The best way to make sure such a pattern doesn't exist is to have the boss disrupt the party in unpredictable ways. Remember - the difficulty of a battle is determined by how much it makes the player think, not by how hard it 'would be' for the PCs. It doesn't matter that they take more than 9000 points of damage from the gnashing fangs of the terrible beast, or that it takes some incredible amount of hits to dispatch it - to the player, these are just abstractions. They're not feeling those fangs. All they're noticing is that if they keep healing with one character every round, they're home and dry.