You carry powerful magic in your veins. However, it is a threat unto you as it is to your enemies. Beware, young one, for all choices have consequences. (bonus=Proficiency bonus)

All spells have range of earshot, and are cast through the chiming of bells. 

Once per day for each:

1st level;  Ranna the Sleeper;            Sleep;                      DC 10;  Backfire affects all creatures in radius, including caster

3rd level;  Mosrael the Waker;           Raise Dead;            DC 13;  Backfire doesn't grant control, and can give Raised free will and wrath on a natural fail

5th level;  Kibeth the Walker;             Plane Shift;             DC 18;  Backfire transports to random plane, at DM's discretion

7th level;   Dyrim the Speaker;           Audible Glamour;  DC 12;  Backfire fails, and mutes the user for the duration

9th level;   Belgaer the Thinker;         Charm Monster;    DC 14;  Backfire initiates effect on you (as cast by target)

11th level; Saraneth the Binder;        Mass Suggestion; DC 16;  Backfire grants the target(s) immunity from all charms for one minute

13th level; Astarael the Sorrowful;   Mass Power Word Kill; DC natural 20; Backfire affects all creatures in earshot, rather than only those targeted. always affects caster