Arena Build

I am just posting a build for now, I'll update and change it to a guide later. So for now i'll explain the build. I mean it is pretty straight forward if you look at it, also I don't main nor am I that great at ADC gods, granted Danz is first ADC I think I have Diamond skin for. Mostly I play frontline warriors or assassin, people you are more aggressive with. Though I do enjoy danz as I feel you can be more aggressive with him due to his kit, so this is the build that is working for me well in arena, and yes I know there is no Life Steal, but it is arena I feel that LS isn't really necessary.

So the idea behind this build is to eventually max cdr added with the 3 sec reduction from malice proc every 5 sec, this is why I max the 3 before Danz's Ult, allowing you essentially constant up time on your 3 and almost constant on your 1 and 2. While also having high crit chance, buffing yourself and debuffing the enemy. The debuffs play to your favor with the constant uptime on your 3 skill, since it provides already a 20% dmg reduc to basic atks + a 20% movement spd reduction, which stacks with the debuffs. This allows you to be more aggressive as long as you aren't taking a bunch of skill shots to the face.

Now depending on who you are up against, either take beads or aegis your choice, but the 2nd item should be Upgraded Heavenly Wings. This allows you to apply a lot of pressure to the enemy team back line, also with the constant uptime on your 3, it frees up a spot to not have to take Atalanta's Bow. Games have not lasted long enough to change out boots for spd pot, so as far as a "Full Build" I have not had a chance to really run one nor do I know what I would change the boots for yet.

For reference, without aura's coming from your allies and assuming you hit your basics for the proc's off your items, your looking at:
402 basic atk dmg
310 from physical items
2.2 atk spd
75% crit chance, 90% after you hit someone with your ult and atk them from Failnot
20% pen + 10% pen from Wind Demon
40% CDR + 3 sec reduc every 5 sec from Malice

Effects Assuming everything Stacks:

Poisoned Star- 15% dmg reduc and 20% slow + Danz 3 assuming these all stack= 15% dmg reduc + 20% basic atk dmg reduc + 20% slow from item and another 20% from 3 skill. = 35% basic atk dmg reduc (if they attack with basis) while in your leaf field and a 40% spd reduc if enemy is in your field

Wind Demons- 10% pen + 20% atk spd and movement spd + Danz 3 skill 40% movement spd in leaf form at max rank = 60% movement spd if wind demons is active while in leaf form for 5 sec. 30% pen + 20% atk spd with no movement spd reduction + 20% movement spd from WD while inside your 3's circle and not in leaf form.

Ichaival- 3 stacks max +15 pwr per stack and enemy atk spd reduc 10% per stack = 45 pwr and -30% enemy atk spd.

Malice- 3 sec skill reduc every 5 sec if you crit with basics, this does not affect your ult cd. 30% cdr (40% if you have Potion of Power or Blue buff active which you should) Danz's 3 last 5 sec and leaf form lasts 4 sec so total ability time is 9 sec, it has a natural 16 sec cd without any cdr and a 10 sec cd with 40%, if you max the timer on your field before turning into a leaf, you essentially will have 1 sec left after exiting leaf form. If you max the leaf field's 5 sec + 3 sec reduc from malice, you basically have your 3 up about 2 seconds after becoming a leaf.

Now as I said I am not an expert ADC, this build works for me and I have not seen anyone post it yet, so I felt like sharing what I use, granted I change it up for LS and other normal ADC builds from time to time, but this build has been the most fun so far.