This mod would change either potions and/or barrels to have a roguelike dynamic to them, mirroring the random potion system of most old school roguelikes.
In example, if you come into a room with a set of three barrels, one barrel may be normal, while the other two may be a strength and defense barrel that boost your melee strength, and add to your defense respectively.
The mechanics for interacting with the barrels are as such:
If you damage and detonate the barrels, they unleash an aoe with their respective effect, so an imp nearby would then have enhanced melee damage AND get armor, as would of course the player.
A secondary way to interact is to get close and hit use, and the player can pick up the barrel, letting the player choose to A: throw the barrel which will promptly detonate it as normal, or the player can DRINK half the barrel, which takes few naked, vulnerable seconds, much more if they drink the whole barrel.
If the player drinks half the barrel, the effect is understandably half, in example a defense barrel will grant a player 80-100 points of defense when you drink half, or a strength barrel gives the player a good minute and a half of berzerk strength enhancement.
If however the player drinks a barrel whole in short order, the effect is not only powerful, but the player may get a debuff that lasts for a short time.
A defense barrel drunk whole will give 210 points of defense, but the player is slightly slowed until their armor is whittled down to 180, or they move around for 30 seconds.
A strength barrel will grant the player a massive melee boost, but they cannot hold any weapon but the fist or chainsaw, and they may end up slashing/punching uncontrollably at random intervals.
Another example could be an adrenal boost, which when drunk by half, increases the run speed of the player a decent bit (About half), and increases their weapon speed slightly (0.5 increase) , when drunk in full, the player runs fantastically fast, and their weapon speed is enhanced 80 percent, but they have a hard time controlling their movement as they slightly slip when slowing from maximum speed, and they can drop weapons accidentally from all the jittering.
Drinking too much from barrels (Or potions) gives a dangerous "sick" debuff in which the player will periodically hurl caustic liquid that can damage foes, and harm and buff or debuff monsters randomly depending on the effects drunken. It harms the player slightly over time as well, and in small chunks when they hurl.
Then comes the dipping
, the player can "dip" their weapons into a barrel/douse it with a potion, to give it an effect for a small period of time. This even works with the standard barrel, which gives weapons a slight explosive effect, not too much, just a little, and for rockets, it enhances them a bit, giving their aoe about 0.8 wider radius, and a 1.0 damage enhancement.
If such a mod had both barrels and potions changed up, I think a fun mechanic would be to let the player pour potions into a barrel and promptly throw it to cause a large explosion of wild effects dependent on what was poured in. The player does not have long to throw it though as the blend is unstable!
The player can find empty potion vials to fill up by barrels, with a potion filled up taking half of what is in a barrel.
Effects I have in mind include the following:
Strength: basically berzerk.
Defense: adds armor.
Speed: adds speed to movement and weapon firing speed.
Buoyancy: gives the player a floating effect when coming down from a jump, also when jumping, can be dangerous if the player is pushed around while under the effect!
Cryo, freezes entities caught in explosion for a short time, if drunk down, slows the player but gives a little "ice armor" effect, giving resistance to fire effects, slowing the player down slightly, and giving them a small chunk of armor points, without replacing the armor type they have on (If none is worn currently, they get a specialized ice armor type that is slightly stronger then bare armor shard defense.)
Trippy: monsters effected will move and attack randomly, and periodically "die" for a few moments before getting back up, and periodically "hurl" creating slippery entities that cause slippery movement for all players/monsters moving on them. If the player is effected, colors will get weird, and there will be a slight distortion effect on their vision, and periodically "fake" enemies will appear in front of them.
Brain Juice: Monsters enhanced by this will be more tactically intelligent, equating to them attacking a little faster and gaining a "dodge" move, as well as the inclination to rip apart the player emotionally by slinging dire insults their way. Also they can pick up barrels and throw them. A player under the effect will temporarily get the map revealed to them, and they can utilize health and armor items better, getting twice the boost from them, and lastly they can get a new option with barrels and potions, letting them mix up an arcane mix (And mixing it with their charged BFG) to create powerful summons!
I know some mods kind of do this, but I think a dedicated mod designed to work with other mods would be a fun way to spice things up!