This is Inevitabilis from Puella Magi Madoka Magica, Mahou Shoujo Madoka Magika, 魔法少女まどか☆マギカ or whatever the heck else you want to call it.

There is another transcription of this song available at Eternal Sonate. Our transcriptions differ slightly in a few places, but I couldn’t say which one is more correct.