Here's a rough idea. Feel free to alter or expand it.
Shiva:

Arena is the standard Primal size. Shiva will call pillars of ice that need to be broken continuously. The party will need to dedicate one or two party members to this task for most of the second phase. These pillars are strong against piercing strikes, but very weak to Fire and Blunt damage. They will go down after a few weapon skills. Standing too close to one for too long may cause players to become bound until the pillar is destroyed. The damage of Diamond Dust will depend on how many pillars are still standing.

Meanwhile Shiva will bombard the rest of the party with Heavenly Strike (giant falling icicle dealing area damage) and other ice abilities. The tank will need to continuously move her around because the position of the ice pillars is entirely random (not dependent on enmity list).