So, an idea that came to me out of nowhere.
Caiphas Cain; LIVING SAINT OF THE EMPEROR!
So, say in the events of Duty Calls as Cain faces off against Killian and steals back the Shadowlight, a disaster happens where events unfold slightly differently. Say Jurgan trips over as he, Cain, Amberly and her retinue retreat for her shuttle as the Tyranyids assault the Sisters of Battle (who are almost gleefully happy to sacrifice their lives to atone for their hosting of the renegade Inquisitor). And in a trillion to one shot as they just reach the shutte (that proves to Cain once and for all conclusively that the Emperor really has a nasty sense of humour and considers him a personal source of entertainment), Jurgan trips as a detonation next to him goes off.
And the Shadowlight bounces out of his hands, skitters across the ground just far enough away from him for his null field to stop completely supressing it ... and thwacks into Cains back.
There is a considerable amount of pain and shock and light and whatever else as Cain is sure he is now dead. Either from what is about to happen to him, or Amberly putting a mercy bolt in his head to spare him what would happen, but he staggers onto the shuttle and collapses as Jurgan collects the artifact and scoots up and the shuttle takes off. But even with Jurgan right there (or perhaps because he IS right there), something happens and then there is a flash of everything going golden annnndddd he snaps out of it to find himself falling through the air.
Oh and he appears to have wings now, making him look like a rather less heroic version of Sanguinius.
And he's falling to the ground where he has a splendid view of the Tyranyid Swarm like a living carpet of ants crawling up the sheer face of the plateau to overrun the little resistance left in the Sororitas convent as the bulk of the Sisters form up a thin battle line between the convent and the town as the PDF hastily try to drive to assist in the clearly hopeless battle, with far too little firepower to stand up to the swarm.
Oh and Cain? Yeah, he's falling directly at that. But, at the last second in a panic, somehow, in an instinctive manner, he levels his descent and sweeps grandly along the defence line all glowing and glorious which stops anyone identifying him as a Gargoyle and shooting him down as the sisters (who were praying hard to the Emperor for salvation) have something they never would have expected grace their battle line, setting down directly atop a Rhino where all can see him; witnessing the ascension of an Imperial Hero to a living Saint!
At that point, Cain notices the swarm, well, swarming towards them and his very well honed 'I want to live' instincts kick in because the Sisters are far too busy falling to their knees and praying at him in rapture than using their bloody bolters! And so calling instinctively on his Commissar skills he roars (very VERY loudly it seems!) for the Sisters to stand and shoot - and they promptly do so glowing golden, shooting with accuracy and skill that even Space Marines would grudgingly admire, buying Cain enough time to have a very quick look around to try and figure out how the fuck he can get the fuck out of here.
Happily, he see's Amberlys shuttle coming in (far too slowly for him!) to try and land behind the line (nice of her to come back for him and even if it's going to end up with him taking a trip to some Inquisition black site, it beats certain death!). And just as he is about to take a quick jaunty stroll thataway ... the Rhino, its driver filled with the golden glowing zeel Cain has apparently missed, guns it forward as all the Sisters CHARGE into the oncoming bioforms high on ultra-zeal and Cain is more than a little horrified of course as he is on point, with this fucking crazy nun inside driving right at a fraking Hive Tyrant!
And because Cain will always try for the 1% chance of life over the 100% chance of death, he tries to leap into the air and call on the power he can feel to fly the FUCK out of here ... but simply jumps up very high. Which is very very impressive of course and looks glorious!
And then he arcs down.
Straight at the Hive Tyrant.
But all the time he is desperately, frantically, pulling on the psionic power around him, coming to him, unknowingly connecting to the sacred ground of the convent which for thousands of years has been marinated in the warp by the sheer faith of countless generations of Sisters, pilgrims and ecclesiarchs focused through the jubilant and utterly believing sisters charging in after him as he comes down screaming (in righteous Imperial anger and rage according to the hundreds of propaganda pieces made out of the various vid systems watching this from all different directions - but really in sheer terror) right at the Tyrant. Which tries to slice him out of the air only for Cain to meet it with his chainsword on his sheer well trained instincts ... which is glowing bindingly gold right now ...
And it strikes and a surge of energy blasts into the Tyrant ... and then THROUGH it and its connection right back into the local Hivemind and in an instant ripping into the minds synapses and transmitting from creature to creature to creature all the way up to the local Norn Queen in deep space which explodes in a glorious one-in-a-million confluence of events of Golden ichor that causes the Hive Mind itself to flinch like it reached out and absently tried to pickup something scalding hot. Deciding that perhaps it'll just write that splinter fleet off and stay the fuck away from whatever the fuck that was. And go pick on the Tau or something. Who don't seem to have this Warp Bullshit.
Locally, there is just a brilliant golden explosion and for a half kilometer in all directions Nid bioforms are torn asunder but loyal faithful Imperials are merely blessed by the Emperors grace as all across the system the Nids go into full Feral mode and instantly start turning on each other in an orgy of self destruction that makes it almost child's play for the Imperium to clean them up! As Cain stands there, utterly stunned to find not just the sisters, but all the PDF who arrived falling to their knees around him and wildly chanting his name as the local ecclesiarch who was standing with the sisters screams loudly to behold the glory of the Emperor made manifest; Caiphas Cain; LIVING SAINT OF THE EMPEROR!
As Cain looks off to the side to find Amberly is now there with her people pushing up to the front, the Inquisitor staring at him and the two of them communicating with a look.
As Cain understands fully that she is clearly torn between the desire to call in an orbital strike right now ... or fall to the ground rolling over laughing her fucking ass off because unlike everyone else, she gets the joke.