Mmmm might be a slight op- ofc this varies by the opponent's deck.
to break it down.
1) Field spell-both sides(Might count in favor of card, except that it's easy to work around-this serves little as a balancing factor)
2) Discretionary(only targets duplicates)
2a) Duplicates are essentially killed - comparitive to eternity minus locking mechanic(cards are placed on bottom of deck)
2b) Damage is dealt = sum of all removed cards' cost
3) Targets any card type(creature, spell, perm)
4) Affects hand as well
Before any discussion this has essentially 4 core mechanics to it. Already a bit overloaded.
As for balancing- a players deck generally contains multiple copies of each card usually ranging from 4-6(not counting pillars/pends)
-Most decks focus on using those multiple cards, many focus on getting out as many as possible.
--Furtheremore some decks focus on swarming using duplication effects.
This card wouldn't be used early on, its nature requires time for full effect(a point in its favor)
-however becasue it deals damage = to the sum of costs; the damage potential is outrageous+it has a built in instakill effect(see above)
Cards are also meant to be designed in a way that having multiple copies is typically waranted and often necessary.
This card would lose its utility after one use in most cases.
Personally I cant stand insta-kill cards. I know this is felt by many. Either way I have two suggestions----
1) Eliminate the removal effect.
or
2) Eliminate the damage effect.
Essentially you've got 2 cards shoved into one, pick one and stick with it.
I also reccomend changing the damage mechanic no matter what, set it to a specific value.
On a side note- I agree it needs a name change, I know what Occam's Razor is, I've done reports and research on it. It doesn't fit this card.