Discordance is as simple as the description allows it to be. It does indeed swap MH% from primary skill to secondary skill as well as swapping CD, Multi Attack , Extra Attack and Mana Cost and vice versa.
What this means is that Primary Skill almost acts like special skill and special skill acts like primary skill due to swapped values and instead of Primary Skills , Multi Attack with Extra Attack will be affecting special skills.
In this typical LOHKO Scenario that is here and was once used heavily, this is how discordance would work in the build.
The arrow would deal the 1050% MH from the MultiShot special skill but it also becomes more expensive in Mana , gains 6 sec cooldown and loses the effect of Multi Attack and Extra Attack since it essentially acts like a special skill at this point. The reason this combo was so powerful was because you could get one shot arrows if you built correctly with the fire dot as insult to injury. Even the guidedshot could still be buffed by hero point in discordance mode.
Another good example is Discordance Chakram Orb build like my builds I recently made. The scenario here is having Chakram gain 200% DMG from Orb as well as the CD and higher mana cost but the Orb gains 300% MH and it is no longer 200% MH. This orb can be buffed by things like Multi Attack, Extra Attack, orb hero point and many other factors to get really high MH% but it is extremely potent due to the rapid 10 hit frequency or 0.1 seconds per hit . The Chakram Primary Skill has an exceptional 300% MH compared to other primary MH skill with highest reaching 150% and others at 100% MH starting point so essentially, the chakram is a huge jump in DMG.
Notes:
Hero Point values don’t get swapped so Orb hero points still affect Orb even in Discordance but it won’t transfer to primary skill to keep good balance of skill DMG whilst using discordance.
Skilled does work with Discordance but again, the mythic isn’t swapped and only affects Primary Skill regardless but that is a good thing because it makes primary skill discordance builds that much more powerful.
Discordance only works on MH Skills otherwise it would be extremely OP with spam stealth , ridiculous OH% values with the shield .
Attack Speed does work on Discordance skills but CD of the skills will be minimum 0.5 CD.
Discordance doesn’t work on Procs. The reason why it used to do this is because of a bug which allowed things like procs to be affected by discordance which could have spawned potentially OP builds as well as reduce potential power of the process on certain discordance builds due to that limitation. This means procs can finally be more free in their effects if you use discordance and you can no longer make insane MH% procs appear too easily anymore.
This also nerfed my orb build significantly as the process no longer was affected by discordance but when I tried skills such as Storm, it really helped but now that I made it a good balance/tank orb discordance build ,it’s not always needed.
Basically Discordance is as simple as the description allows it to be .
You can thank me latter. 
