Board Thread:General Discussion/@comment-31147727-20190603183014/@comment-39394247-20190909170949

My headcanons:

His HP is somewhere between 1 and 12. However, his attack patterns are quite powerful, and he can probably beat all but the strongest of the normal encounters. Comparable to Alphys in overall power level.

Gaster was Sans' and Papyrus' father, and Alphys' mentor, and Alphys also knows how to use the Gaster blasters.