Nope, apparently Crystal Spheres change shrines to your devotion type. The stained page just makes some ultimate badasses spawn to murder you. Here's hoping they drop some great stuff once I can actually take them.

But i can't defeat them anf so i can't use any sanctuary know to heal. What to do? Tried it for hours now.

Have you tried backtracking or going to the next Sanctuary or speedrunning to The Candlelit Lady? (To forgive sin)

beggar is the earliest place

Im at a loss. I get the same. My char will just use it ON the weapon

Equip it, place yourself in front of the altar : you'll get a "desacrate" prompt.

I´d like to know, too. If you use the crystal sphere to take over peacefully I guess you can just "convert them".But once you manage to get the super strong enemies that spawn down, will the sactuary be empty ? I really wonder...

did each other sanctuary spawn guardians and become convertable or do you need to desecrate each one

I panicked when I put myself in the same blunder, I didn't want to desecrate any Creed's only sanctuary, so I swapped Creeds before retaking my original faction's sanctuary. I lost access to ALL fast travel via Calling Horn while being incapable of obtaining Bloody Writ as I intended (didn't know you had to 'lose'). For anyone interested, all sanctuaries owned by the Creed you just desecrated will be hostile now, I don't think you need more than one Stained Page per faction, but don't go on a murderous rampage just yet.

It's worth noting, you can still travel via a guide to sanctuaries owned by creeds you didn't just go to war with.

The 'Candle-lit Lady' near Village of Smiles will Forgive Sin, once you do that, you'll regain access to all your fast travel guides. You can pretend it never happened and rejoin your old faction.