Exodar Banner
Sold by Irisee. For clarity, this is a banner that you summon and set on the ground. Think of it like a racially proud Archmage Vargoth.
The 
Exodar Banner is a placeable toy purchased from a vendor in Icecrown that lets you plant a Draenei faction banner on the ground anywhere in the world.
Guide awaiting review
Find Vendor Irisee
Head to Icecrown and find Irisee at 76.2, 19.2. She sells the Exodar Banner in exchange for Champion's Seals, which you earn as a Champion of your faction — for most players, this is purchasable on your very first day as a champion.
Purchase the Banner
Buy the Exodar Banner from Irisee for 
15 Champion's Seals. If you change your mind, you can sell the item back to reclaim your seals. As a bonus, adding this toy to your collection also unlocks the opposing faction's banner counterpart — two toys for one purchase.
Tips
To use the banner, right-click it in your inventory and your cursor will show a semi-transparent preview — click to place it on the ground. It works indoors and outdoors, lasts three minutes, and shares a three-minute cooldown with all other banners, so you cannot place multiple banners at once.
See the video guide for a full walkthrough of the banner placement mechanic.
