I was explaining it to my alliance the other day.
Greed is a reverse taunt. Only the targeted hero gets anything.
Imagine a lineup of Lianna - cKrampus - Bera- Khufu - Pengi
If you cast Greed on Khufu, and then smash tiles into Krampus to set him off, Khufu is the only one that gets the attack up and a minion.
No taunt, no attack up, no minions for anyone else.
There is strategy involved. You want to ideally target a wing or a hero away from any buffs that work for ‘nearby’ to prevent them working too.
Hope that helps!
Edit - also includes healing, so only the greed targeted hero gets any healing.