Take it when you want a low-model-count, Monster-heavy list built around multiple C'tan as your primary threats, and you're willing to pay the 2 DP and the per-C'tan points surcharge. It suits players who value a resilient, board-controlling brick of god-shards whose aura passively boosts the whole army's damage. At 2 DP it leaves 1 DP for a cheap support of scoring bodies.
Sample gameplan: deploy two or three C'tan (e.g. Transcendent + Nightbringer + Void Dragon) with a cheap objective-holding backfield. Advance the shards up the centre so overlapping 6" (or 9", paying 3 wounds) Distortion Fields blanket the midfield β every enemy inside is unravelling, so all your attacks gain +1 AP. Cripple the scariest Vehicle with Animus Damper, Advance-charge with Quantum Goad, chip units with Molecular Erosion, and when a shard falls, Disharmonisation Cascade detonates it on 3+. Punish Fall Back with Phase Melding and reanimate your infantry with Mass Transmogrification.