Adding to what Selur said, the original Diablo required a graphics card capable of 16-bit color at a minimum resolution of 800x600, a SoundBlaster compatible sound card, 16 Megs of RAM, and a Pentium CPU. The original was probably written in Visual C++ using DirectX for graphics acceleration. Blizzard was famous for making things system-friendly using DirectX. I've even been able to run Diablo on a modern system and it still works mostly!
Considering that Amos would require an extension for graphics card support and a better compiler for execution speed, this puts Diablo firmly in 68060 territory at worst and Vampire 68080 territory as more ideal. The killer is the real-time lighting effects that require all the tiles to be redrawn on each frame. Even without that, the color depth of ECS chipset graphics is a 5 or 6 bit color depth so it won't ever look as good without a graphics card, even if you modeled all the tiles in Lightwave (which you'd have to do to get the full light shading effects).
An example of an Amiga game with light-sourcing but overhead instead of isometric is BOH. BOH requires a PowerPC accelerator to run at full-speed and is written in C using SDL as its graphics support.