When coming up with non-randomly generated characters for an otherwise random game, sometimes you start with an (perhaps obvious) idea: This one should be able to freeze enemies! This one should be able to steal enemy health! Sometimes you start with no idea at all and figure out what to do.
Squid is the second monster I ever drew for Realm of the Ghost King (the first is Ghost, who you'll hear more about next Saturday) and it hasn't changed at all since (the only one to never undergo any revisions). The design is an obvious reference to Cthulu and the name an adknowledgement of that.
Initially Squid was kind of boring. No double move like Ghost, no teleport like Morel, no explosions or energy sapping. Its special attack used to just be regenerating health (which is what BOT_3000 does now) and its passive used to be regeneraing a bomb for every close kill. This made Squid fairly overpowered but also not very interesting.
At some point or another I added friendly AI into the game, which are just enemies that target other enemies instead of the player. I don't recall if that was added for Vlad's special attack or for Squid, but it's one of my favorite additions to the game since it can create some interesting and even unpredictable scenarios. Really the main drawback here is only two monsters allow you to benefit from the friendly AI. Vlad, as mentioned, can temporarily convert enemies to friends, but Squid can summon a permanent ally in the form of an undead skeleton (or, I suppose, just a large skull).
Initially summoning an ally was very expensive. It cost the usual two souls but also cost one health. While this limited the number of skeletons you could summon to your health minus one, it also meant you couldn't summon one as a last ditch tactic when you had one health left. There are no such restrictions on any other special attacks, so it was kind of unfair. I eventually removed the health requirement, but then you could summon four or more skeletons at a time depending on how many souls had you banked. It made the game kind of crazy if you just spammed skeletons into every level. It was a waste of resources to do it most of the time, but it seemed silly to allow it.
The final compromise ended up being only allowing one skeleton in the level at a time and blocking subsequent attempts at using your special attack. Skeletons generally don't last long enough where you'll want a second special attack, and if they do survive to the end it usually means there aren't any more enemies anyway.
Titan is more of a product of the first method of thinking. The basis behind him was: "What if there's a monster with a lot of health... and also he can make himself invulnerable!" Invulnerability is a fairly standard thing in a lot of games. The main thing you have to make sure is that it doesn't make the game too easy. Since becoming invulnerable takes from your valuable soul pool it's hard to overuse it in most cases, which is good. The only revision I made to invulnerability was making it last for an extra turn: four instead of three. Three turns felt too limiting and it was still useful as a way to bail yourself out of a bad situation, but there wasn't much to be done if you wanted to plan something with it.
Also unlike Squid, Titan also underwent some pretty major revisions. Back when the game was called "Ghost Realm" and every character was a ghost (which just meant they all floated), Titan looked like a floating shield and was named accordingly. In fact internally in the game code he's still referenced as "shield".
As always, happy Saturday! The final three monsters will be introduced next Saturday.