system
Given the following post, respond as if you're commenting on Reddit:
human
[GoT/SPOILERS up to S4E1] Why is the magical stuff becoming more powerful during this time?

Does it co-incide with a long winter coming?

When Danaerys was in Qarth, the House of the Undying guy said that his magic is only strong thanks to the presence of the dragons. So without them around the powers of practitioners like him might be diminished from what they once were.

What Melisandre can do seems to be something that is not known about and wouldn't be believed if not seen.

Certain kids discovering they have the ability of wargs. It seems like everything magical is gaining power at the same time.
gpt
It's not because winter is coming, it's because *change* is coming.  The Warlock in Quarth was wrong, he can't use magic because the dragons have hatched, they're both because there's a change in the world.  This change is also what's causing more White Walker and Whight activity, and it's what is allowing the priesthood of R'hollor to do more than parlor tricks, and what's leading certain people to inadvertently discover their Warg or Greenseer abilities.

What exactly the nature of this change is is uncertain.  Maybe it actually is the dragons, but this is unlikely, maybe it's a certain someone's awakening Greenseer abilities, maybe the machinations of an old god, or maybe something else.  We've not been told yet, and might not be.