Gangplank passive idea
TL DL:
Alright so lets start with a blank slate. Here's how the new passive could work +8% crit +3% per nearby ally GP receives +25% bonus crit damage this cannot stack with other sources of bonus % crit damage. the 25% bonus crit portion could be converted into a poison. Poisoned champions within 400 range of gangplank are slowed by 10%
Or maybe the +25% bonus crit damage could be on his placed on his q.
Thought Process With the removal of atmas its difficult to fit crit while remaining a bruiser. If you want to have a chance to feel your crits.
So here's how you could fill that missing crit chance. At first I thought of giving him crit in a fashion similar to irelia's tenacity: I would giving him a passive with +5% Crit chance +3% per nearby enemy.
But then it occured to me that GP is about rallying the team so why not have it give him more crit per nearby ally. Per ally: +8% crit +3% (per allies since only 4 allies whereas up to 10 enemies) or have it as 4% crit plus 4% per ally. The goal is to get on average around 15 extra crit. (like you would from atmas).
Viable builds could go:
-
or
-Aura GP:


(Locket and Frozen Heart to help team survive thereby keeping his crit chance.
with 5% to 10% in crit runes. it would be normal to have around 40 to 50% crit chance. which I think is a sweet spot to have it at for it to happen often enough to notice it. Since he's good at poking with q it would be good while sieging if your teammates are nearby.
The idea is that IE should be reserved mostly for ADCs and assasins. But going crit without any form of +% crit dmg is a bit underwhelming. Hence, the second part of his passive: receives +25% bonus crit damage this cannot stack with other sources of bonus % crit damage. He could still get IE and benefit from it, but it wouldnt have to be core for his crits to be effective. Or maybe the +25% bonus crit damage could be on his placed on his q. While still not being able to stack. In which case IE would be more useful for regular auto attack that crit.
but i don't think IE should be core for him, it coud still work well in solo q and be fun, but this wouldn't make him as dependent on it to maintain his crit plank identity.
perhaps the 25% bonus crit portion could be converted into a bleed or poison, like the wicked hatchet...
Wicked Hatchet Unique Passive: Critical strikes causes your target to bleed for an additional 60% of your bonus AD as physical damage over 3 seconds. Bleeding champions within 400 range of gangplank are slowed by 10%
So borrowing from this: GP receives +25% bonus crit damage this cannot stack with other sources of bonus % crit damage. this 25% bonus crit portion is converted into poison damage. Poisoned champions within 400 range of gangplank are slowed by 10% cannot lifesteal off this extra damage, but that shouldn't be a big issue for GP since he has oranges and is encouraged to build hp/resistance items to be a bit more front lineish.
Thoughts?
Wicked Hatchet
Unique Passive: Critical strikes causes your target to bleed for an additional 60% of your bonus AD as physical damage over 3 seconds.
Bleeding champions within 400 range of gangplank are slowed by 10%