Ill go through the systems , not sure if it will help though

First of all you got ruins and dots
As a caster your moto is to keep that gcd rolling. Keep using ruin 3 unless you have to move or have to weave ogcds, theyve added an aoe equivalent in the form of overburst (its just tribind).
Your dots are your biggest boon in this job, always keep them up, the thing you have to keep in mind is to not overwrite them so you will cast them only when the old ones are at like 3 seconds. You also have bane in order to spread them to multiple enemies albeit at a small dps cost of -60%.

Here we come to the first gameplay change, Pet actions are no longer individual from you they are gcds, they are also more potent than ruin 2. The game here is to minimise your use of ruin 2 to the absolute minimum , you get 2 of them every 30 seconds so plan accordingly.

For ogcds
Aetherflow has been replaced to the far inferior energy drain/siphon , single target and aoe version. You use it on cooldown and it will provide you 2 aetherflow to use fester or painflare. You got 30 seconds to spent them before energy drain comes off cd.
The other change to our system comes with the destruction of the aetherflow//trance chain. for level 60 it doesnt do much its a hard 55 seconds cooldown that allows you some free movement and gives you deathflare, for now using it on cooldown will do the trick , you can also instantly use deathflare since besides the instacast ruin 3/overburst provides no dps buff anymore.

Going a bit backward at level 56 you get provided with tridisaster an ogcd that applies your dots instantly, it has 50 seconds cooldown but trance resets it upon activation. Here your dot cycle is created, you will use the cooldown in order to minimise gcdcasting your dots , every 2 mins your applications should be one from tridsaster then trance to reset tridi and use to refresh when the duration of the dots is at 0 , Then the third aplication will be from second trance reset and the 4th will be gcd casted dots. Tldr youll use 3 tridisasters and 1 miasma bio every 2 mins. This sequence can change , for example at level 80 we overwrite dots on opener to get them under buffs.

Level 64 gives further ruination which upgrades ruin 2 to ruin 4 everytime you use pet action 1 (egi assault 1) , for now they are nothing but a bonus providing you with extra movement instances without dps lost.
At level 70 you get bahamut every 2 trances , Bahamut attacks on your every gcd and locks you from all pet abilities. for now lets ignore it.
at level 72 you get bahamut per 1 dreadwyrm trance but the second trance becomes pheonix trance so its still summoned every 2 and you cant just say no to it
At 74 you get your second further ruin allowing you to get ruin 4 from egi assault 2, you will have to be carefull to not overcap ruin 4 as you can only hold up to 4 and anything more gets lost.
at level 78 your bane gets upgraded to put full duration of dots on other enemies
Level 80 you get pheonix basically your second demi summon, Here are some key differences between pheonix and bahamut. Bahamut and his trance are seperate allowing you to delay his activation without losing on trance cd , pheonix on the other hand is combined with pheonix trance to provide you with its effect , ruin 3 and overburst get upgraded into 2 instacast combo actions, which means that you cant delay it without delaying trance something that you dont normally want to do. Not only that pheonix has its own activation spell everlasting flight , its an aoe regen healing for a total of 600 potency , this however provides problems for the ai in the form of losing one auto attack unless you do some dancing around it.

Overall thats the gist of it , i hope i didnt confuse you (though i propably did). i hope youll enjoy the job