Needing to Damage a specific creatureType. or DoT.

Hello, i had to create a account since i was literally unable to figure out a way to do this otherwise..

I must mention i'm using a 1.12.2 capable mcreator plugin.

I've been pulling my hair out over a situation..

I am using my mod in a 89 mod modpack, one of those mods includes lycanites. everything is working fine except one thing. My damage over time weapons were causing Lycanites categorized under the UNDEAD creature type to heal from the instant damage potion effect caused by the swords to simulate higher DoT, and i cannot select their entity.type from MCreator since it only loads vanilla data.

I wasn't sure how to make a mob take a Damage over time by the effect of a sword hitting it normally without potion effects (i'm not that experienced with MCreator yet). since everything is higher scale HP i needed to find an alternative to fire damage dealing only 1 hp to their massive 300hp or so. My solution to this was applying potion effect of instant damage or instant healing to affect certain mobs. but it caused other mobs labeled as the undead creatureType in other mods to be healed.

I need one of two solutions, in MCreator format please: 

1. either a example code to Damage creatureType undead
2. or A code to Cause static number DoT to everything i hit with the fire sword. in this case the DoT would be 40 for example.