Nahiri and Nissa enter an Akoum Skyclave together, initially united by the wish to help Zendikar. The ruin preserves the scale of the old kor world. Nahiri values the architecture as evidence of what has been lost; Nissa finds companionship in an elemental that guides them through the living growth inside it.
They recover a key that can lead Nahiri to the Lithoform Core. When she uses its power to still the Roil, the elemental and surrounding life are destroyed. Nahiri sees relief from chaos. Nissa sees the cost of imposing that relief on a world whose creatures cannot be separated from its spirit.
Nissa confronts her, then goes to Jace for help. Their conversation carries both distrust and grief for Gideon. Jace wants the artifact brought somewhere it can be studied; Nissa wants its threat ended. From the outset, the problem is not a shortage of concern for Zendikar. It is that concern gives each guardian a different definition of what may be sacrificed.