can we get a summary of Zatanna’s interactions with Swamp Thing? And/or Madame Xanadu?
(Sorry it took a while to answer to this. Not being able to answer this has been bugging me for a while)
Outside of JLD, the most notable interactions I can think are:
-For Swamp Thing:
Although her Dad died as a guest star in a Swamp Thing, Zatanna and Swamp Thing never really interacted in that specific arc.
There was a Swamp Thing mini series in 2011 by Len Wein (Swamp Thing's other Dad) and artist Kelly Jones (perfect fit for the title) which revolved around Swamp Thing/Alec Holland looking for a cure for his condition with his friend, Matt Cable which leads the two of them to Zatanna's place.
Continuity wise, it a bit of a mess. What with Matthew Cable being...well....alive...human and...not one one of Morpheus's crows. Plus references to Alan Moore's Swamp Thing run but ST is a human turned to swamp creature instead of a swamp creature who thought it was human. That said, Alec Holland was brought back to life thanks to the events of Brightest Day so that's not as egregious as Matthew Cable.
Zatanna is the magician who gets the biggest focus. Her characterization is the same as her preNu52, same goes for Phantom Stranger and Etrigan. But this mini fits neither the Pre Nu52 continuity nor the Post Nu52 continuity. I think it can be enjoyed and read on it's own. It's just stuck in a weird middle ground continuity wise because it was published in a time when nobody at DC was sure if the Nu52 was a full, clean slate reboot or partial reboot and no one could decided what should remain in continuity and what shouldn't.
-For Madame Xanadu:
The first major story to have Zatanna and Xanadu interact with each other was Spectre Vol 2 #7-8 titled 'Pieces of Zatanna'. It's a rare body horror story involving Zatanna where she finds her limbs and other parts of her body disappearing and returning but she knows they are not her original limbs.
So Zatanna quickly runs to Madame Xanadu for help. Although this is the first time readers see Zatanna and Xanadu interact, the two are already aware of each other.
The story is meant to resolve loose ends from Zatanna's final appearance in Justice League of America Vol 1 #257 as well as give Zatanna some closure for her fathers death in Swamp Thing #50.
Zatanna later appeared in Spectre Vol 2 #11, this time, of all things, the limo driver who chaueffer's Xanadu, Bronze Tiger and June Moon to a meeting arranged by the Spectre involving all the magical beings so they can discuss their roles in the human world. Not sure why Zee couldn't have just teleported them there, but then again, maybe they just wanted to enjoy a nice drive and limo is implied to be Zatanna's.
Years later, in Madame Xanadu's own series Madame Xanadu #9 we learn that Xanadu and John Zatara had dated in the past which goes a long way towards explaining how Zatanna knows her.
In Spectre Vol 3, around #16, there was a story arc where an Eclipso possessed Spectre went on a rampage. Zatanna appeared in the story arc but didn't get to interact with Xanadu as she was recruited to by Phantom Stranger to be on his team alongside Etrigan and the Inza Nelson Doctor Fate. Xanadu made her own team with Father Creamer and Ramban. Notably it's Xanadu's team that ends up succeeding at stopping the Spectre's rampage but cutting to the heart of the issue and confronting Corrigan's spiritual crisis directly.
Aside from that, Xanadu and Zatanna often appear together in ensembles during events like Obsidian Age and Day of Vengeance but they are not always notable.
I always thought that Xanadu could be a cool step mom figure for Zee since the latter operates in a male dominated world.
I haven't read Bendis Justice League in full yet but around the time the JLD back up feature was getting cancelled we did get to see Zatanna and Xanadu team up to fight a possessed Black Adam in Justice League Vol 4 #73: