As soon as Alcusus connected with the spatial rift by using that key like item, he immediately felt the vast power that the realm held. This feeling was very intoxicating and Alcusus felt like he was the almighty. But he knew that this feeling was just an illusion and losing himself in this illusory feeling was very dangerous.
So he composed his mind and started to control the key with all his might. This key allowed him to get some authority over the spatial rift but he was nowhere near controlling all of it. But he really went all out with the control and pushed this item a bit further he should be able to control the space around this area to attack Rein.