Winter's Append is a mod primarily developed for personal use between myself and friends, without any planned focus or goals.
As of right now, there are very few items, but there are several effects and a new potion type added.

Items

• Tonics
  
  Tonics are a new potion type with four unique traits. One of these is that they always last a base twenty minutes (configurable), regardless of ingredients. The second one is that they have three slots for effects. There are many combinations you could make, whether it's filling a potion with Minor Health Boost, stacking different types of resistances, or otherwise just buffing yourself. The other traits are that they take quite a while to drink and can be stacked up to three.

Blocks

• Tonic Stand
  
  This is a block based on the Brewing Stand which brews a new item called Tonics. It uses two types of fuel, the only required one being Blaze Powder. The second type, called Purity, is increased through Gypsophila flowers. When there is insufficient Purity, brewing times and Blaze Powder costs are greatly increased (2.5x and 2x, respectively). Recipes can be viewed through the EMI plugin by checking the uses of the Stand.
• Gypsophila
  
  These are a new flower type that can be found in specific biomes (primarily forests and plains (savanna and badlands in 0.4.X)), used for fueling the Tonic Stand. Despite being a short plant (one block tall), they can be fertilized with bone meal to obtain duplicates, with random chance. Soul Meal can be crafted to obtain duplicates with far higher odds.

Effects

Effect IDs have their names sorted. Things like winters_append:minor/pos/health_boost for Minor Health Boost and winters:append:minor/neg/speed for Minor Slowness, or winters_append:immune/thorns for Dethorning.

• Minor Versions
  
  There are several effects that add little bonuses to your stats, smaller than Vanilla ones would. This includes effects like Minor Health Boost, which gives one heart instead of two, and Minor Speed and Slowness, which give a 5% increase or decrease respectively. There are some other effects in this category, though, like Iron Skin, which gives one armor point per level.
  Also included are Physical and Projectile Resistance, which reduce damage by 5% from direct damage (Zombies, Spiders, Endermen) and projectiles (Arrows, Shulker Bullets).

• Immunities
  
  Hate being poisoned? Tired of getting hurt by berry bushes? Want to fall a longer distance? Those are the things these kinds of effects do. Antivenom prevents the poison effect while it is active, allowing you to handle Cave Spiders with ease. Dethorning will reduce damage from Thorns and berry bushes by 50% per level, and Kinetic Resistance will protect you from flying into walls and falling to your death, starting at 50% and increasing by 10% per level.
  There are downsides to having these effects, though. Antivenom will reduce damage you deal by 10%, Dethorning will lower your attack and movement speed, and Kinetic Resist will lower your armor points.

• Enchantments
  
  Ever wanted Silk Touch temporarily, or just a bit more of a boost to your fortune? Thankfully, these effects have you covered, providing a single level of both! Higher levels of the effects increase the rate that they trigger, with their base levels not activating 100% of the time.