Blackspeech and Celestial

Blackspeech and Celestial are languages not meant for mortal tongues to speak and can be quite dangerous to use without the proper training or preparation.  For most, knowing the language means understanding what is being said when it is spoken or written down.

Blackspeech is the combined dialogue for fiendish outsiders, whether they are devils or demons.

However, for those to speak it, they must make a DC Charisma check to avoid taking damage.  This damage cannot be resisted, but it can be negated if someone has immunity.  Psychic for Blackspeech and Radiant for Celestial.  The DC Charisma check is 10 for short messages; 15 for moderate messages; and 20 for complex  messages.  If someone fails the check, they take 1d12 points of the corresponding damage type per level of the check (i.e. 1d12 for DC 10; 2d12 for DC 15; and 3d12 for DC 20).