Jun 3, 2015, 12:09 AM

@SG
Try it with:

$^\+adice ([0-9]+)d([0-9]+)\+?(-?[0-9]+)?$:@remit %L=<Dice> %N rolled %1d%2[if(strlen(%3),if(gte(%3, 2),+,)%3,)] for [add(die(%1, %2),%3)].

Looks like that might get rid of your trailing -.