Added the unique skill "Killing Stance"

The unique skill "Killing Stance" has been added to Othin. Holders of this skill will increase critical rate when counterattacking.

This effect is a reworking and reimplementation of the original "Wrath". It increases the critical rate before battle, and can be activated together with the Ambush skill, but if the opponent has Crusader's Scrolls, the critical rate will be 0, including the increased value from this skill.

Othin also has the "Wrath", which is now FE4 style, now he is very easy to get critical hits. Note that there are several other units that have "Wrath", but I decided to put this skill only on Othin, because I did not have the image of aggressively aiming for a critical with a counterattack, except for Othin.

Skills that change values before combat will not be nullified by Nihil.