Base ion core

[Drifting death]

Hi base ion cores.
I have one, but I have alliance members asking how to get them, to which I say it's a random drop from attacking NPC bases.
Has anyone got any ideas or tips on how to get one.
They say they are hitting NPC 34 bases still no drops.
Thanks DD

[Kerean]

You get it by upgrading 30 buildings to Level 15.

[Drifting death]

Thanks ����