Spinel Tonic

The Spinel Tonic is a lunar equipment in Risk of Rain 2.

Activating the Tonic will dramatically increase the player's stats for 20 seconds, but after this effect wears off there is a random chance to gain a special item, dubbed a "Tonic Affliction." A player who has Tonic Afflictions has all stats reduced by 5% (-5% per stack) if they are not under the Tonic's buff.

The chance to get an affliction is affected by Luck. This means that with a single, the player's chance to get an affliction is reduced to 4%. However, having a single instead will increase the affliction chance to 36%.

The negative effect can be avoided if the buff is kept up continually, since the game does not roll the affliction until the buff expires, and all afflictions have their effects negated while the buff is active.

The stat bonuses (other than armor) for this buff are unique in that they are multipliers. For example, not only does the attack speed buff give 70% bonus attack speed, it makes all other attack speed buffs 70% stronger, so a would give 25.5% bonus attack speed instead of the normal 15%.

Math
The percentage reduction to all stats (besides health) is determined by the formula

Trivia

 * Before the Skills 2.0 update, using a Shrine of Order would remove all Tonic Afflictions from a character.