Complex sentence: Daenerys' combined Dragon-Dothraki-Unsullied horde then conquers the slaver city of Yunkai; but the lords of Meereen antagonize Daenerys by killing child slaves and burning the land to deny her resources.
Split into simpler sentences: Daenerys' combined Dragon-Dothraki-Unsullied horde then advances on the slaver city of Yunkai. However, the lords of Meereen antagonize Daenerys by killing child slaves and burning the land to deny her resources.