A few moments before the situation where Adrian vanished…
Adrian already knew that he will not be able to land a killing blow on either of the two enemy gods unless he makes himself easy to target. He knew that the God Loki would want to kill him first as the enmity between them is at its peak. He needed to cerate a chance where he would be vulnerable to any tricks and deceptions.
Since Sirius' domain is still active, Adrian knew that he could still use the effects of the illusion as long as he perfectly timed it. He started by activating the Nether Domain to make it look like he is giving his all. He then summoned Dodu at its smallest possible form and immediately swapped with his scythe weapon.