QoL: Concentration

You may focus on one positive concentration effect (affecting the PCs, also could be called a buffing spell) and one negative concentration (affecting NPCs, also could be called a debuffing spell) effect. Spells such as Investiture of Ice could fall into either category. To determine which is which if unsure, ask the GM.
If a spell caster maintains concentration on two spells, a failed concentration check causes both concentrations to be lost.