If you were really skillful (using the same items listed above), you could do what Don Giani and Helicalpuma showed here, where you could do 3 hits under AG's nose, back up a little, do 1-2 more hits, and repeat. It required a lot of skill and practice to do it and made the slugfest that was AG into a really fun fight.
Now it's next to impossible to kite Ancient Guardian with a Magi & Club, where you can only really do 1 hit every time AG does his charge.
It would be greatly appreciated if this was fixed. I really dislike cheesing Ancient Guardian with pillars and graves. The actually fun and skillful way to kill Ancient Guardian early game is gone now with this.
This is how the fight is now:
This is how the fight is prior to this patch: