flame_tiong said:
pff... the author doesnt even trying to explain anymore...
Kosmo entechelia (or whatever they are named) connected the school to the magical world and guess what: Everyone was in the school.
Al was stuck at mahora academy because his life was necessary to maintain the seal on the lifemaker, now that this seal is broken he can go wherever he want.
Simply once the two world started to merge enough it became possible for people from Mahora to take action, this include the headmaster, Eva, Al and Eishun.
Once on the battleground Al summoned Kurtz and Takamichi, since we've seen teleportation magic since a very long time ago I don't see it weird at all for a well versed mage such as Al of being able to use it.
There's nothing weird in that, nothing that need to be explained by the author as well.
Now let's move on the special case.
Imo
Asuna magic = what Fate's group use to send people to KE.
As we've seen Negi's group was sent to KE once (A fake one but well) so you should understand how the princip works -> It simulate a dream world around everyone.
Now Asuna, even tough she have a terrifying power output, is still limited to her power, that is she wouldn't be able to cancel an attack stronger than she is herself or send someone stronger than herself in KE.
This same Asuna that is fighting so that her power do not get out of her control so that Fate's plan do not success may have created some turbulence in the flow which lead to Rakan making use of his insane power output to overpower Asuna's magic and return to the magical world.
Of course this is not 100% sensical because we do not know how magic work, we only know from what we have been told but we should assume that it was something theoricaly possible in this world, just out of reach of about everyone but Rakan.