I just got a new drummer in my band who is phenominal but im having problems writing over his 250bpm blast beats. im just not used to it. ive been doing chugs like suicide silence does over them but am wanting to do more black metal like stuff. what should i do?

Well playing some single note scale ideas will work. Of course synchronizing your picking with the blast beat or trem picking stuff. Listen to some Deeds of flesh or Spawn of Posession or other bands in general for their blast beats and what the guitar players are doing over them to get a general idea.
Here is a list of bands to check out.

Disgorge
Deeds Of Flesh
Origin
Necrophagist
Suffocation
The Faceless
Decrepit Birth

Listen to all kinds of different death metal bands and try to listen what the guitar players are doing over the blast.

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understand you dont need to play at 250bpm if the guy drums at that tempo.
You can play divisions of the drums..
for example, 125bpm would be just as good.

actualy, matching note-by-note is a bit less intresting than having different stuff at different(but compatible) temps going on.

see...

DA-DA-DA-DA-DA-DA

is less brutal, headbangable and sexy then

DA-da-DA-da-DA-da

or

DA-da-da-DA-da-da-DA-da-da

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Listen to what your favourite bands do. You'll notice they just play normal riffs they would play with any other drum beat. It's cool to play the same riff with different drum patterns to give a different feel at the same tempo.

Put a metronome on at a tempo and play a riff. The drums can then do anything they want at the same tempo, give or take accents, and it will fit (to an extent).

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