Hi there,
If you want to run it on classic Amiga, you can download DevilutionX on Aminet:
http://aminet.net/package/game/actio/DevilutionXThe readme includes a link to a shareware version of Diablo, which can be used to try the game. The full version can be purchased on GOG (Good Old Games):
https://www.gog.com/game/diabloDevilutionX is also on AmigaOS 4, MorphOS and AROS if I remember correctly.
Hope this was of help. :-)