-[this.] is not needed.
-CHANCES should be static and not be added in constructor.
-How constructor addition for Romp should look like.
addStartNpc(ROMP);
addTalkId(ROMP);
-Also created a collection method for addKillId so now you can add directly keyset as a parameter.
addKillId(CHANCES.keySet());
-Use equals instead of equalsIgnoreCase.
-Since MathUtil.MATRICE_3X3_LINES is only used by this script just add that constant in the same script.
Patch:
https://pastebin.com/qp8mycpY