This is strange. Necrons outnumbering Tyranids? I am playing 50 power level vs. 2x 25 power level detachments. My army list via Battlescribe is as follows:

Battalion Detachment [50 PL, 6CP, 990pts]

Configuration

Dynasty: Mephrit

• No Force Org Slot +

Cryptothralls [2 PL, 40pts]
2x Cryptothrall: 2x Scouring Eye, 2x Scythed Limbs

• HQ +

Overlord (Indomitus) [5 PL, 90pts]: Is a Custom Character, Warlord, Warlord Trait (BRB): Inspiring Leader

Plasmancer [4 PL, 80pts]

Skorpekh Lord [7 PL, 130pts]

• Troops +

Necron Warriors (Indomitus) [6 PL, 120pts]
. 10x Necron Warrior (Gauss Flayer): 10x Gauss Flayer

Necron Warriors (Indomitus) [6 PL, 120pts]
. 10x Necron Warrior (Gauss Reaper): 10x Gauss Reaper

Necron Warriors (Indomitus) [6 PL, 120pts]
. 10x Necron Warrior (Gauss Reaper): 10x Gauss Reaper

• Elites +

Canoptek Reanimator [5 PL, 110pts]

Skorpekh Destroyers [7 PL, 135pts]: Plasmacyte, Skorpekh Destroyer (Reap-Blade)
. 2x Skorpekh Destroyer (Thresher): 2x Hyperphase Threshers

• Fast Attack +

Canoptek Scarab Swarms (Indomitus) [2 PL, 45pts]
. 3x Scarab Swarms (Indomitus): 3x Feeder Mandibles (Indomitus)

Conclusion

Not winning. Scary alien monsters are scary, even when you are a robot zombie army. I didn't bring the right units to handle an army of Hive Tyrants, a Lictor, a Trygon Prime, Hive Guard, and Warriors. The only usual troops they brought was ripper swarms.

Lessons learned: be more defensive. Focus on objectives. And buy some models who can deal with multi-wound monstrosities.