this is why i dont read fantasy books. renly dying was stupid. if stannis can just send a black demon goon to kill anyone then the war's over. and yet he hasnt done that again since last season.
melisandre told him earlier this season he cant because his "fire" is real low, that shadow baby shyt took a toll on him. thats why he looks 10 years older this season and why she had to go and get someone else with "kings blood" (gendry).
i agree it is kinda stupid, when i read that shyt in the books i was like
but
thats the power of the lord of light, r'hllor.
Plus all this shyt is only possible now because of the dragons being born, thats what the red comet in season 2 represented. Magic returning. The only time the show went into this was when the warlock had danearys chained up and told her how his power is amplified around her