Okay, so who is Abigail? Abigail is Wendy's dead sister, and Wendy can summon her using Abigail's flower. The flower can be crafted for 1 nightmare fuel and 1 mourning glory. Abigail serves as a minion to Wendy, fighting enemies for her. She attacks with an AOE, which means she is good at farming many weak mobs, such as bees or spiders.

You can control Abigail with Abigail's flower. You can soothe and anger her. Soothing Abigail makes her stop attacking, and return to you. Angering Abigail makes her seek out mobs to fight. However, this doesn't include Webber's spiders. There might be more minions she won't fight, but I don't know yet. If you build and decorate a Sisturn, which costs 3 cut stone, 3 boards, and 1 ash, It will produce an aura of 25 sanity a minute, and Abigail will level up 4 times faster. Abigail leveling up increases her health from 150, to 300, to 600. It also increases her light aura. She also inflicts vulnerability on enemies she attacks. This vulnerability lasts for 2 seconds, and adds 10% damage. But, to Wendy, it is 50%, which with her 25% penalty to damage, puts her at 125%. Basically, if you are using her right Wendy can deal more damage than normal even with her penalty. Abigail affects Wendy's sanity. When summoned Wendy gets 15 sanity. When dismissed she loses 15 sanity. When Abigail dies, Wendy loses 30 sanity. No, you can't have more than one Abigail.

Wendy has a special tab called the ectoherbologly tab. This tab is dedicated to making potions to buff Abigail. Each of these potions needs mourning glory. Wendy can help pipspooks to get mourning glory. She helps them by following them to their lost toys. If you stand still near them they will orient themselves around you in a certain direction. Head in that direction to get to the lost toy's rough location. Once she gets close enough, the pipspook will begin to pulse. The intensity of the pulse tells you how close you are to the lost toy.

• Revenant restorative costs 1 spider gland and one mourning glory. It boosts Abigail's natural regeneration, upping it from 1 per second to 3 per second for one day.
  
• Spectral cure-all costs 1 telltale heart and 3 mourning glory. It is a more concentrated version of revenant restorative. It regenerates less total, as it lasts 30 seconds, but it is 20 a second instead of 3 per second.
  
• Unyielding draught costs 1 log and 1 mourning glory. It doubles Abigail's shield duration from half a second to a second. She puts her shield up after she is attacked.
  
• Distilled vengeance costs 1 living log and three mourning glory. It is essentially better unyielding draught, as it doubles the shield, but things that attack Abigail while her shield is up take 20 damage.
  
• Nightshade nostrum costs 1 stinger and 1 mourning glory. It gives Abigail her nighttime damage buff (15 during day, 25 during dusk, 40 during night) all the time.
  
• Vigor mortis costs 1 honey and one mourning glory. It massively boosts Abigail's speed. If a player ghost haunts the potion they get a short burst of speed.