Why do I believe there's room for improvement in the first place? Compared to cultists, most of Blood's monsters pose a very low level of threat. Many of them are nearly harmless in melee range as long as the player simply evades their feeble attempts to bite or scratch him. The time constraints in Blood's development and cut content also means that Monolith had more good plans in mind besides what made it into the final product.
-------------------------
Gargoyle
- Unused sprites for the gargoyle are part of a soaring animation, possibly for an attack or a more natural looking animation for long flights. To make the gargoyle a more formidable enemy, it can have a mode whereby it tries to attack the player by swooping in on him with its talons. Having hitpoints lower than 50% would reduce the gargoyle to its vanilla behavior.

- Awakening from statue form in earlier Blood versions was transitional and animated rather than instantaneous as it is now. From what I understand it was probably removed to due to how vulnerable the gargoyle was left during the transformation. I still think the animation looked well done, and maybe it could work better were it quicker.
Stone Gargoyle
- Smaller and 75% weaker variant that can be placed more frequently in maps.
- The player can simply lure the stone gargoyle into close range where it becomes nearly harmless. It should be given the opportunity to use its ranged attack in more situations, or perhaps even be restricted to that attack alone. The ranged attack is currently too lethal, crumbling the player and his spirit armor effortlessly, its damage should be halved... I've tried facing the stone gargoyle "fairly" at a distance a few times and there is somewhat of a pattern to its eye attack that can be predicted, but evading it still remains a tricky dance that I haven't mastered. I should mention that it's easy to block with DUAL VOLTAGE TESLA CANNONS.
Gill beast
- One of the few dangerous non-cabal enemies that probably wouldn't benefit from upgrading. Facing the gill beast in its natural element is already a risky test of reflex. On land, it may be slow but it's still more dangerous than a zombie. Only quirk is the way they always fall sideways on death begins looking weird after multiple kills. There are unused backwards-falling frames in Blood, and adding them for more variety may be an improvement
- Completed gib effects

Hell hound
- As it stands, hell hounds are not dangerous unless they catch the player off-guard. The firebreath is too focused and unidirectional to have a chance at scathing an agile player, but that may be compensated with an improved bite. Could be upgraded with a jumping bite attack that triggers once player gets too close for fire breath.
- Completed gib effects
Bloated butcher
- The "dead weight", but not a dangerous foe at all. Puke attack may work better if it acts more like the pod's projectiles with splash damage and low velocity.
- Make thrown cleaver faster and fix the immunity to it granted by crouching
- Unique animation for burning death such as the one found in the alpha. The regular one is just a resized "burning dude" that doesn't t fit the butcher's image that well, in my opinion.

Phantasm
- Make projectiles homing?
- Less predictable scythe attack, something like the Quake knight's continuous slash-and-charge until flinching from damage.
Spiders
- Ability to descend from webs
- Ability to climb walls and ceilings
- Green-yellow blood
- Jumping bite?
Cerberus
- The guardian of the gates of madness, a huge monster with two vicious maws and napalm breath just needs to be approached up-close and personal for it to become another harmless ammo sponge. Restricting cerberi to the napalm breath as their sole attack should make them fearsome enough.
Beast
- The beast is an interesting enemy that behaves like a beefed-up arch-vile from Doom. But all the player needs to do is maneuver close enough so the beast can't utilize the stomp and resorts to clumsy swipes with its claws. From that point, it's just circle-strafe and shotgun. Removing the melee attack would make it very dangerous, but the stomp will have to be nerfed to become slower as it's currently overpowered, along with reducing the beast's hitpoints and raising the painchance threshold.
Bone eel
- In Blood, the bone eel just instantly dies from the air exposure when it tries to follow the player and surfaces as a result. Sprites from the alpha suggest that this creature was not supposed to be so haplessly vulnerable to the environment.

--------------------
As for the inevitable downside, pitchforking many upper-tier monsters would become impractical which would interfere with some gameplay mechanics and level progression, but I feel the trade-off is worth it due to the fact that so many of them are not a danger at close range, and this is one of Blood's few flaws.
On the bright side, it would encourage the player to seek more ammo, search for secrets, try out new weapons and strategies, etc. and Blood's dangers will not be limited to the cabal. It will mean more ways the player will get hurt in, and that means paying attention to fire and spirit armor along with an incentive to search for it.
Zombies should probably stay the way they are since there needs to be a cannon fodder class that doesn't demand ammunition. Rats are already enough of a nuisance for an underequiped player, especially since their biting attack is faster than that of other creatures. I didn't bother with choking hands either as they are already a wholesome enemy.