Echidna's Authority.
Eren activated the effects of the monster artifact and freed his demon beast Argo at the same time. Since he did what he did with Har Jahar's body while his time-element spells were active, most of the monsters weren't caught up to what he had done.
Roar!
A lion's roar was sounded in the surroundings as the monster's artifact's effects washed over the audience all around Eren. The latter also spread his mana sense while acting his wrath domain in a unique way.
Eren now had better control over his elements and his abilities than ever before. He had come to realize that he didn't need to stab his heart to activate his wrath domain. All he needed to do was keep his hand over his heart and mimic the effects of the heart getting stabbed with his newfound control over the heart muscles.
