When I break a totem of undying, It got used AND I died right after because of "death.attack.magic.player" what

Please try the beta build below and see if the issue still persists.
Due to missing context, I guess that you are on minecraft 1.12.2 (which this build is for)
firstaid-1.6.14-BETA.zip
Simply unzip the jar file and place it in your mods folder. Don't forget to remove the old firstaid file.
If this fixes the issue, I will make this an official release soon
EDIT: new file, new fix, should work for real this time

Hi! I'm having a similar issue as well. I'm using the 1.14 version and when I die the totem is used though it doesn't save me from death.

Should be fixed by 9cb326f for 1.12, version will be release on CF this week. 1.14 and 1.15 will receive the fix soon(tm) as well