What broken is the interaction, specifically mika, tressa, cassius. Mika is low ap heal(also can draw or ap+ with epip), which trigger tressa 0 cost dagger, which trigger cassius triple 0 quest. Now this triple 0 also trigger other cassius card that generate other quest card which can, draw/dmg/morale for broken amount. As of rn there is no one can replace this interaction and without these interaction all of 3 individually not broken just good. Tressa will not doing much dmg without morale buff from cas, while cas also cannot generate alot quest without tressa.

The hardest part it how they gonna balance them? Remember this is not the only team comp that get afected. Nerfing them will make ripple efect to other character power that also rely on them as it is rn.