Note that the biggest number drastic instability can reduce by is -4.
Numbers bigger than 5 are not listed.
Negative quanta cost: Spell costs 0.
Negative ATK/weapon/damage: Heal the opponent.
Negative HP: Death at the end of the turn.
Negative healing: Damage you.
Negative ability cost: Skill costs nothing.
Negative quanta generation: Drains quanta of the particular element.
Negative shield: Deal more damage.
Negative mark buff (from dirk/gavel/bow): Decrease damage. May heal.
Negative ATK buff (Rage potion, blessing): Decrease ATK.
Negative HP buff (Plate armour, blessing): Decrease HP. May kill.
Negative card draw (SoSeren, SoBra, Precog): Nothing.
Negative nova: Drain quanta from each element.
Negative dissipation (Absorb quanta): Gives quanta of entropy(unupped)/random(upped) element.
Negative dissipation (Negate damage): Increases damage.
Neagtive poison: Give purify counters.
Negative bone wall (7 when played): Card does nothing (Although you can't get down to minus 7.)
Negative bone wall (Gain 2 when a thing dies): Lose shields.
Negative boneyard: Nothing.
Negative stone skin: Reduces maximum HP. May damage.
Negative warden delay: Reduce the delay, then remove delay if there is any.
Negative earthquake: Gives pillars/pendulums.
Negative photosynthesis: Lose life quanta.
Negative SoBra: No card draw.
Negative freeze: Reduces freeze, then remove freeze if there is any.
Negative purify: Poison.
Negative solar shield: Increase damage. Light quanta gain is unaffected.
If you're somehow < 5 maximum HP, miracle can kill you if it gets a positive draw.
Negative sky blitz: Sky blitz doesn't happen. Positive sky blitz lasts multiple turns.
Negative procrastination: Nothing.
Negative sundial: Sundial is destroyed instanty.
Negative SoR: You cannot use skills this turn. You can get positive SoR and get 6 cards from one nymph.
Negative Cloak: Instant destruction.
Negative vampire ATK: Heal the enemy, damage your opponent.
Negative drain life damage: Heal the target, damage yourself.
Negative nightmare: Damage yourself, heal the opponent.
Negative SoV: Increase opponent's maximum HP.
Negative dim shield: Instant destruction.