Through various of her contacts, lackeys and contracted criminals, Ira Almasy has decided to contaminate several wholesale ingredients used to concoct healing potions at St. Mungo's Hospital.
A high enough dosage of all contaminants on a weak enough patient (children and the elderly) besides the Staghorn Mushroom would be enough to eventually kill them.
Comatose patients will likely awaken a week or two after consumption.
Potions Contaminated
Healing Potions - often contain Horklump or Staghorn Mushrooms
Painkillers - often utilise Willow Bark, trace amounts of Horklump or Staghorn
Sedatives - including potions like Draught of Peace, often contain Syrup of Hellebore
How strongly each potion is contaminated is up to writer's discretion.
Where
Potions from St Mungo's and London based apothecaries.
Sources
Willow Bark and Syrup of Hellebore - Drammes Apotheke, through a network of their suppliers
Ground mushrooms - within the UK (perhaps through The Worshipful Society of Apothecaries)
Streeler venom solution - likely to have been bought and made by a specialised breeder in North America who may be difficult to find
Heinz Werner gets more than he bargains for on arriving to certify a large shipment for Drammes Apotheke. Johann Storm assisted by others, forges papers to ensure safe transport of a large amount of tainted product at Ira Almasy's request. Amongst the shipment is hellebore.
The shipment arrives just outside Paris, France where some of it is processed into potions by Drammes Apotheke's staff, bound for London in bottles of sleeping potion like Somniculose.
Agatha Mendip dies. She was 23 years old, admitted to Plant and Potion poisoning with her partner Ruben Pardo. Smoked gillyweed laced with juice of durian fruit, which caused paralysis. (Horklump or Staghorn Mushrooms)
Camille Kendrick dies. She was 6 years old, admitted to Spell Damage at 3:30pm. After getting hold of her father’s wand and managed to remove all the bones in her right foot. She had been given skele-gro and potions for the pain. Flynn Hughes delivered the news to the Kendrick family. (Willow bark)
Perry Evarard dies. He was 90 years old, admitted to Spell Damage after splinching. He had been given a sedative as he had not calmed down, even after dittany was applied. Otherwise, he was in good health for a man of his age. (Syrup of Hellebore)
Kenneth Norris dies. He was 27 years old. Patient for 9 years in Spell Damage, Janus Thickley Ward. Prone to delusions after a botched attempt of putting a memory into a pensieve—when it was too distressful for him, he was often sedated. (Syrup of Hellebore)
As a result of Poisons and Painkillers, Johann falls ill from Syrup of Hellebore, and Balfour rushes him to hospital. Arcturus receives them. Between blue glowing vomit, the possibility of death, a sleeping log and a growing patient death-count, none of them are having a particularly good night.
"He was logging sleeping potions. He's addicted?" Balfour wasn't certain if Arc would be able to confirm it, considering confidentialities, but he didn't need a verbal response - only to say it out loud himself. "Don't answer that. Never mind." He breathed out slowly. "What is it that you need me to do right now? And what's the matter with him? Is it poison? Glowing vomit isn't... he said it wasn't normal, even for what he takes." For a moment Balfour recalled the way Johann had said his name in the bathroom, flooded by genuine fear, and his heart foundered anxiously at the memory.Balfour Spectre
Ruben Pardo dies. He was 26 years old, admitted to Plant and Potion poisoning with his partner Agatha Mendip. Smoked gillyweed laced with juice of durian fruit, which caused paralysis. (Horklump or Staghorn Mushrooms)
Timothy Dale, 5 years old, brought into poisoning ward. Admitted to Potion and Plants Poisoning for accidental ingestion of magical pesticides. Was being treated with painkillers and getting better before abruptly showing signs of poisoning and going into comatose sleep. (Staghorn Mushrooms)
Sheldon Kingston dies. He was 8 years old. Admitted to Spell Damage to recover from sores inflicted by protective jinxes from his sister’s diary. He burst into laughter, and the healer thought it had been part of the spell damage. (Horklump or Staghorn Mushrooms)
Josie Zinns dies. She was 2 years old. Admitted to Plant and Potion Poisoning, She was the youngest patient Jules Deville has ever lost. Josie came in giggling, seemingly delighted by the fact that she had eaten something that had made her polka-dotted and ticklish. (Staghorn Mushroom)
Claire Pepper dies. She was 45 years old. Admitted to Spell Damage, Janus Thickley Ward over 2 years ago. Victim of a horrific accident through obliviation that had shattered her memory. She had been a loving mother to Ambrose Pepper and Tim Pepper and wife to Francis Pepper (though by the time of her death, ex-wife). Claire had been suffering from migraines as a side effect of her current treatment—which had been promising, but showed no evidence of long term success. She had been prescribed pain potions to counteract that. (Willow bark)
Balfour Spectre visits Johann Storm on St. Mungo's third floor after attending the funeral of a contamination victim, Chardonnay Kane (6 years) in Cornwall. Johann apologises for keeping secrets.
He didn't look away from their locked eyes. "If you're a mess then you're my mess, don't you know?" His weepy eyes crinkled slightly at the sides in affection. "We'll do whatever it takes. It... um. It scares me too." Terrified him, really. Few things genuinely did and if he were anywhere but the ward Balfour would have been tempted to light a cigarette. He drew closer down to Johann, gently kissing the tip of his nose. Better than tobacco. "I won't lose you," he said quietly.Balfour Spectre
Johann Storm is discharged, but Arcturus Hollingbury is too caught up in the deathcount to properly feel happy. Timothy Dale, thankfully, also awakens and looks to be in recovery.
Trailed by a Daily Prophet reporter and photographer, Ira makes a visit to the hospital for charitable purposes. The timing of her poisoning is impeccable.
"Do I look twenty?" The croak was odd, but recognisable, and despite his stern features, a genuine, happy smile broke out across the Deputy Headmaster's face as both hands clasped her right hand.
"Of course you do." He replied with a hint of a relieved laugh in his tone. As she launched herself over the edge of the bed away from him, towards Cassidy he released her hand instinctively to let her do as she needed. As long as it wasn't bright blue and glowing as Camille had mentioned Johann's had been, he would still celebrate.Ignan Storm
Head Healer Miranda Elliot calls a meeting at her bedside with her Heads of Floor to understand the situation while she has been in a potion-induced slumber.
Gladys-May Shufflebottom brings in one of her children after mistakenly administering a healing potion tainted with the poison from December. As an antidote is now available for all of the poisons, it is a relatively simple job to fix.