Self-explanatory. I tried to go for a mythic approach for the background - as Henry is a mythic figure in his own way (due to his performing extraordinary feats like Hercules that wouldn’t be possible to do in real life).

Here, the myth here would be that he’s trying to tame a stallion who is black as the night, can only be found when day and night collide, and most importantly, can create thunder and lightning (hence the lightning bolts, star-shaped effects on the earth and the sound waves echoing off them. I originally had in mind a grey mane and tail for the horse but I liked how the purple came out so it stayed haha.