Just as Kael felt, the upper limit of the power of these self-discipline puppets depends on the upper limit of his own power. As long as they have not caught up with him in terms of realm, the Life Treasure Tree will continuously extract more energy, converting it into continuous Level Experience Points.
Kael could clearly sense that it would only take a month and a half for these self-discipline puppets' strength to completely approach Aister's. Aister would then, with the power of control from the [Crown], further break her own limits with their assistance.
If possible, Kael only wants to stay in his own territory now, until the energy supply of the Elemental Furnace completely maximizes the strength of the self-discipline puppets.
Then Kael would take these puppets, who temporarily couldn't be further enhanced, and with the further expanded domain, head outside to let those noisy guys experience what it means to be a Magic Monarch of the Holy Land like no other!