Anc's Arcane Blast

This is s highly unstable spell. Casting this spell creates a blast of arcane energy, causing the target to suffer 10 force damage, plus 1d20. This damage can crit as normal on a natural 20 roll, as you perfectly channel arcane energy. However, due to the unstable nature of this spell, if you roll a 1, you fumble your attempt to tap into the arcane and you reroll the d20. On a 2-20 roll, the spell fails and is lost. On a 1, the you then roll damage with yourself as the target of the spell, including double damage on a critical. If this damage reduces you to zero hit points, you are unconscious for 1d20 rounds, regardless of healing. If the damage kills you, your body explodes, dealing 5 damage per spell slot level plus 2d20 to everyone in a 1d20 foot radius

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, the damage increases by 5 for each slot level above 2nd. When cast with a level 5 spell slot or higher, you also roll an additional d20 whenever a roll is called for.