How is spirit visage on fiddlesticks

I think it would work with the CDR + Heal amplifying, but could potentially be better ;)

depends on who he's going up against.

Fiddlesticks "does" have close to triple the base damage of most AP carries provided all his abilities strike optimally. He reaches 2960 with an optimal combo (max dark wind bounces, max drain duration, max crow storm duration).

most champions with a decent burst rotation are within 100 damage of 1000 base at level 18, doubling that with 450 AP or an overall 2.25 ratio. 2960 is pretty much end-game Nasus levels of free damage if you want to build tanky, and more damage than most AP burst will get if they pursue a 450 AP core-build (within an average ~33 minute long game at any rate).

That said - max crow bounces, max drain duration, and max ult duration happening with Fiddle isn't anywhere near as likely as an optimal QWER with most AP burst champions. Fiddle also has a 5.85 AP scale on his QWER rather than a typical 2.25, so he isn't locked into building tanky like a typical champion with tons of free damage like Nasus.

if you can reliably pull off an optimal fiddle combo vs. your opponents: you can go full-tank and still kill squishies in 1 combo, which will make tank-fiddle a nightmare for your opponents to deal with. Worth noting MR is about 1/3rd the price of AP for what it does and HP is even more cost-efficient: so if you're up against a very magic-damage heavy team, MR + HP and bonus healing effects is a really solid buy.

Against a team heavily reliant on slows for CC with very magic-heavy damage ( ) would be a solid item.

Against a typical team-composition that's only going to let ~50% of your combo hit any given person, and with existing though? Visage is far from something I'd default to with Fiddlestick's core build.

TLDR: in the right situation it would be amazing.

Abysmal is so good on him though. The extra MR from spirit visage seem to have diminished returns.