The main axis of this deck is centered around the 12 fight spells in this deck! These spells can act as removal because all of our creatures (except Phyrexian Obliterator) have deathtouch, and if we use Phyrexian Obliterator we force our opponent to sacrifice permanents!
Importantly, we should keep in mind that Diabolic Intent lets us tutor ANY card in out deck-- land, fight spells, creatures, etc... So, even if we find ourselves without a fight spell, keep in mind that we can use Diabolic Intent to go get any piece of the puzzle we need, be it the fourth to cast Phyrexian Obliterator, a fight spell, or any creature (including Phyrexian Obliterator).
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Bushwhack can help us stay on curve or act as a fight spell. This is a very useful card early game to keep us on curve if we don't draw land, and after to act as removal by using one of our deathtouch creatures to fight an opponent's creature, and (of course) to have Phyrexian Obliterator fight an opponent's creature and force them to sacrifice permanents.
Primal Might is another fight spell, but it allows us to pump a creature in case we might want this one to stick around after the fight! REMEMBER that you do NOT have to pay anything for if you don't want to! You can pay just to cast this spell and it will be a fight spell. The ability to pump a creature is OPTIONAL!!
Prizefight is a solid, instant-speed fight spell that also gets us a treasure token! So, it is effectively a 1-mana fight spell we cast at instant speed! This is actually a pretty good card and I'm surprised that it doesn't see more play in the Pioneer format.
Tail Swipe is a fight spell with modest (conditional) upside-- and an instant, which is not common for these fight spells! Works great! To be able to do this at instant speed is pretty nice.