I'll do you one better: Grey Knights summoning Daemons. I know, I know, it's specifically disallowed. What my opponent did was allied in Codex: Inquisition Inquisitors and sanctioned psykers who can take Malefic powers (unlike Grey Knight inquisitors), then used the massive Warp Charge pool he had from all his Grey Knights to pump out daemons. Once the first wave of Daemons are out, it doesn't matter that your Sanctioned Psykers perilsed and probably died summoning them: after all, summoned Tzeentchi daemons can roll on the Malefic daemonology table themselves.
Fortunately, it backfired on my opponent when he failed to summon a Greater Daemon with 8 dice, and that psyker died. He still managed to get out 3 Bloodcrushers, though. In a Grey Knights army.
I imagine you could make it work pretty easily with Guard by spamming Primaris Psykers and Wyrdvane Psykers. Sure, they'd die like flies as you summon things in, but there's something grimly evocative about psykers of a corrupted Guard or PDF regiment killing themselves to bring in their otherworldly masters against their foes. The "Come the Apocalypse" would be... inconvenient from a gaming standpoint, but could be easily explained by the traitor Guard worshiping their newly manifested gods.
Hmm. Damn, now I have to take my traitor guard and mutants models and play a game like this, don't I.
What sphinx of plascrete and adamantium bashed open their skulls and ate up their brains and imagination? Imperator! Imperator!