More poisons

Currently we have only 2 life-draining effects: Wither and Poison, however only Poisono is brewable, but in real life, there isn't just one poison...there are many, and they usually have different effects, so I would propose more "poisons" to the game; this would make the combat bit more interesting, since this effects might be from different sources

Spider Venom

Brewed with a Poison Potion and another Spider Eye. This effect increases its strenght based on how hungry the target is: each 2 missing hunger points, increase the strenght of the effect by 1 damage point, so a starving player would take 11 points of damage every 4 seconds

Cave Spiders inflict this effect

Pufferfish Toxin

Brewed with a Poison Potion and a Pufferfish. This effect increases its strenght the more effects the player has: each effect increases the effect's strenght by 1 point of damage

Eating a Pufferfish grants this effect

Toxins

Brewed with a Poison Potion and a Lily of the Valley. This effect increases its strenght over time: every 10 seconds, the damage dealt is increased by 1 point

Eating a Suspicious Stew made with a Lily of the Valley grants this effect

Poison Resistance

Brewed with a Poison Potion and a Ghast Tear. Grants immunity to Poison, Spider Venom, Pufferfish Toxin and Toxins