This had always been the plan from the very start.
While Legris was distracting everyone, he would sneak his two allies into the Constellation Realm and make them steal a lot of energy for him.
'I had to blend them in with their surroundings, so I mimicked the effects of [The Tower] Arcana and tweaked some aspects of it to make the Spell [Nowhere].' Legris smiled to himself.
Using that, he was able to mask the presence of his two allies, making it so that they would go largely unnoticed.
However, it would have still been possible for them to be detected—especially by troublesome Constellations like Aquarius.
And that was where he came in.
By causing so much chaos that could not go unnoticed, he diverted all the attention to him, and all the panicking Constellations were so bothered about trying to stop him and protecting their wards that they failed to notice Stefan and Ciel.