Hey there!
There's currently a bug in the Arena skirmish which allows you to use items despite the "Not usable in arena"-tooltip.
My friend found this by browsing the Toy box (the new WoD feature, which is accessed through the Collections interface.) and then randomly clicked various items.
Some items you're able to summon
- Wisp Amulet Wisp Amulet - Item - World of Warcraft
- World enlarger World Enlarger - Item - World of Warcraft
- Ai-Li's Skymirror Ai-Li's Skymirror - Item - World of Warcraft
And so on..
You are however not able to summon everything, but still a big part of your Toybox inventory!
Useless or gamebreaking, I don't care - use it while you can