KARMA (KR) Mod
This mod adds a mode that always grants the player an Undertale's KARMA (KR) debuff. Item that switches this mode can be obtained by creating a new player or crafting them at Demon Altar.
This effect drops invincibility frames to zero (allowing attack to hit every frame or 30 times per second). It also applies (to use terms of a general RPG) a "poison" effect to attack: getting hit for even one frame inflicts not just one damage, but also increases KARMA by some amount (depending on attack). Whenever KARMA is above zero, it eventually drains back down to zero in increments of one, inflicting one damage with each drain.
KARMA sets all damage taken by enemies to 1, but increase in KARMA is proportional to damage player originally took. KARMA cannot exceed Player's maximum life of 50% and also cannot cause player's HP to fall below one. More KARMA damage is built up, faster it drains. After KARMA reaches 0, life regeneration is disabled for 10 seconds.
Mod download: http://javid.ddns.net/tModLoader/download.php?Down=mods/SansKarmaMod.tmod