Not a specific plot armor, but one template that drives me nuts is when an author rushes to introduce the antagonist and has the MC blithely bumble into an area or situation that he is clearly not ready for, manage to piss off someone who could crush him like a bug, only to be saved by plot armor for 30 chapters until he's finally strong enough to fight back.
No matter how strong the opponent or what they are (immortals, zombies, undead...) if the MC says that it/he/she dies then they die even if they are far away
An MC being involuntarily summoned (ie kidnapped) and immediately agreeing to the demands to assume full responsibility to stop an alleged invasion and implement genocide, you know, just as a precaution to avert possible future conflicts, without asking for details first or even clarifying what's in it for them, besides "glory and adulation".
MC & his Sect head go to all-female sect. MC is to marry their top disciple (FC) (despite already having 2-3 women he "loves"). MC stares at the beautiful disciples of said sect like a lecher. None like him.
FC hates the idea of getting married to MC, but her Sect Head decided for her. Her friend comes up with the plan to drug MC and sleep with him to change the marriage from FC to her, because FC shouldn't waste her time with some low-life like MC and she needs a "man to take care of her anyway" (something along the lines of "MC is too weak for FC, but should be fine for her friend"). FC does not like the whole rape thing, but agrees to get out of the forceful marriage. MC manages to resist the drug, hears their plan and gets enraged, knocking out the friend and raping FC instead. Turns out FC was practicing a technique that requires her to be a virgin & gets possessed by a demon now that she's not. FC swears to kill MC and flees.
2-300 chapter later MC comes to a region where a monster kidnaps and kills cultivators. During some conflict, MC and a group of ~30(?) other cultivators get kidnapped by the monster and transported to a space where their cultivation is suppressed. Monster starts devouring their cultivation one by one, turns to MC, touches him and leaves, instead devouring another cultivator leaving MC unharmed, because...
tHe MonSteR wAs FC bEiNg cOnTroLleD bY heR dEmOn aNd sHE cOulDn'T bRiNg hErseLf to haRm Mc, sIncE he cOUld nOT be BLAMED FOR RAPING HER, BECAUSE IT WAS HER FAULT AND HE WAS OH SO INNOCENT, AND SHE'D BETTER CONTINUE DEVOURING OTHER CULTIVATORS WHO WERE NOT RESPONSIBLE FOR HER ENDING UP THE WAY SHE DID, UNTIL HE MANAGED TO SAVE HER AND SHE ENDED UP BEING YET ANOTHER MEMBER OF HIS HAREM.
I seriously do not understand why I did not drop that novel then and there, instead continuing to read it for another 50 or so chapters. I read 7-800 chapters of it and it used to be my favorite novel, until I was so fed up with it that I deleted nearly half my reading list, because they had (comparably) minor but similar flaws. I think this novel is the main reason, why for me the Harem tag was one of the first to be excluded from showing up on the NU front page.
