Wild Magic Zones

Across the known world, magic works in strange and unpredictable ways, more so in strange zones where ambient, wild magic abounds. Whether they are found in ancient ruins, ocean monuments, or the forgotten pits of the Underdark, this abundance of unexpected energy leads to some… unexpected consequences.

Ambient Magic Level

The Ambient Magic Level, or AMLv, of a Wild Magic Zone represents the amount of magic in the environment, with more making wild magic Surges far more likely with each casting of a spell.

Commonly, the AMLv of a Wild Magic Zone begins at zero, and cannot go higher than fifteen. Every time a spell is cast, the AMLv increases by 1 for each of the spell’s levels. After the spell is cast and its’ effects take place (or don’t), roll a d20. If the result is less than or equal to the current AMLv, the spell triggers a Wild Magic Surge. Regarding cantrips and spells without levels, they still have the potential to trigger a Surge. However, the d20 is rolled with advantage, and the AMLv does not increase after the casting.

Magic Overflow

If casting a spell causes the Ambient Magic Level to exceed the 15 level cap, a Wild Magic Surge occurs for every level above 15. Then caster then rolls a d20 as normal to determine if yet another surge is triggered.

For example, a Wizard casts a 5th level fireball in an area with an AMLv of 12. The AMLv increases to 15, and the 2 leftover levels both trigger a Wild Magic Surge. On the roll to determine if a surge would trigger normally, the wizard rolls a 14, and so a third Surge is triggered.

Reducing the Ambient Magic Level

Once per spell casting, if a Surge occurs, reduce the AMLv by 1d6+1 levels once, regardless of how many surges are triggered by the spell. The Wild Magic Zone also loses one AMLv for every 10 minutes a spell goes uncast within it, or, to simplify, the Zone reaches equilibrium (AMLv 0) after an hour.

Optional Rule: Sorcerer's Best Friend