I personalty like spark elemental better then hellspark. http://magiccards.info/10e/en/237.html
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Just a thought but you might want to add 4 splintertwins for the hatchers.
Why kiln fiend?
If your looking for sideboard cards then i suggest you add deathmark.
You should add a few scarland thrinaxes to eat the creatures as soon as the come into play.