Triage already exists. Its a 0 pip cost life spell that removes one over time spell from its target. There is also Mass Triage that removes an over time spell from all members of the caster's team.
They are exclusively life school spells, but their treasure card versions can be dropped by some bosses.
The Cow's Pearl Amulet gives its wearer one Triage card and can be purchased from the Bazaar or somewhat easily farmed from Halfang's Cave, which also serves as the game's presently easiest means to farm for gold.
This is a spell that stops over-time spells. I know there may be different levels of this spell, because of the different over-time spells.
this already exists, in the form of the level 35 life spell, triage (which removes damage over time spells). there is also mass triage, a level 72 life spell, which removes one damage over time spell from all teammates.
Spells Triage and Mass Triage already do this.