Hey, I'm going to write a few things as I understand them, and it'd be appreciated if anything I've written is wrong regarding the item.
1) I bind to an ally (my AD). When I use my ult, as long as the AD is close, the AD's auto attacks are buffed by X amount.
2) If an enemy is within my Zekes 'circle', they are slowed by 20%, and my binded allies attacks are boosted by 50% magic damage. - For example if my AD's auto does 600 dmg, it does an extra 300 magic damage totalling 900 dmg?
3) If an enemy is within my circle, and get auto attacked by ANYONE, my circle then does 40 magic DPS and slows by 40%