With the game coming out in less than a month, I'm going to spend a little bit of time over the next month talking about all of the monsters in the game. First, a brief note!
Realm of the Ghost King is sort of unique (or at least I'm not aware of many other roguelikes that do this) in that the player can play as and against all of the same enemies (with a few minor exceptions). You choose from one of eight monsters to play as and you face off against those same eight monsters when you play. While player monsters and enemy monsters do share similar powers, players have some added abilities, but it's also important to know which monsters can do what to better conquer the game.
The second thing you'll hear a lot about are "souls", which are the main currency of the game. Each monster drops a soul when it dies, and souls can be used to purchase stat upgrades, items such as health or bombs, as well as being utilized for "special attacks" which are attacks or abilities every monster has but can only be used by spending souls.
So with all that said let me introduce you to the first two monsters!
Vlad is a bat who has a small health pool but has the ability to sap health from any enemy killed by a close (adjacent) attack. Using this ability allows Vlad to survive some attacks that other monsters cannot. By spending souls (via a special attack) he also has the ability to convert enemies into allies who will fight on your side for a short amount of time. In the gif below you can see a couple of converted enemies, denoted by the skull helmet.
When fighting against Vlad he does not sap health from the player, however he will move backwards a square whenever he is damaged. This means your approach to Vlad needs to be a little bit more considered since he'll move out of direct attack unlike all other enemies.
BOT_3000 is a robot caught in a world of monsters. Thanks to being a robot, it explodes when its health reaches zero, but ejects its robot brain, surviving the process. The explosion will hurt any monsters adjacent to it, which is good because it'll need help getting around after that. Once BOT_3000's body is destroyed it can no longer use bombs, only adjacent attacks. However, if you collect two (or more) souls you can use your special attack to build a new body.
When in full-body form, BOT_3000 can spend two souls to gain one health. This provides an extra degree of survivability without needing to revert into robot brain form.
Enemy BOT_3000 doesn't possess a robot brain, however it does still explode when you kill it, which does require some degree of thought if you don't want to lose too much health. However the explosion works the same as any explosion in the game, and could be used to your advantage if you're clever.
That's all for now, but I'll have info on the next two monsters up on Saturday, and every Saturday thereafter until the game launches.