I was playing an arena game (3-2) and had used kooky chemist to swap the stats of Hollow Abomination (12/2 → 2/12). Subsequently, honorably killing my opponents’ damaged fire plume pheonix (3/2) did not trigger the effect and left me with a 2/9 minion. As I understand, this is a bug due to the stat swap effect of kooky chemist. Best regards,
Ever since the Honorable kill achievement with Hollow Abomination came out
it doesnt work towards damaged minions.
To get the achievement you have to Honorable kill an undamaged minion.
Best option is probably playing it with opponent having Bloodmage Thalnos on board.