Due to the presence of dissonant magical aura(s), outwith your control, your command of the weave has been left disrupted and as such your ability to cast spells has been somewhat diminished.

Any time you cast a Cantrip or Spell, roll an Arcana check to maintain concentration on your control of the weave long enough for you to cast the spell.

The DC for this roll is equal to 10+(Your spell-casting modifier)+(total level of the spell slot used).

I.e A level 2 spell would require an Arcana DC of 14, if your spell-casting modifier for your character was INT and the modifier is equal to '+2' (INT:14/15).

If a Critical failure is rolled, roll a D100, for wild magic table, as the power of the weave overwhelms you, this replaces the spell effect of what was previously cast, as your magic is 'miscast'.

If a Critical success is rolled, you manage to manipulate the weave so that your spell invocation, does not cost you the requisite slot it would normally cost to cast.