I've lived entirely in fel since UO came online, the only place i set foot in other facets is on siege where all facets are fel ruleset, and my primary activity in UO since AOS has been spawning, raiding spawns, and protecting spawns....something...
1. if you're the ONLY pvp capable person at a spawn that could potentially be raided by 20 people, you're doing it wrong
2. every spawn protection group i've ever been a part of has been a mix of reds and blues, if you dont want the count wear them down and let the reds finish them off (it's called teamwork, i hear it works fairly well in online games)
3. I've never come across such a "raid" (as this type of raid does not exist yet), but if it were to happen I would kill them all, and if i go red so what, munch a few pardons and good to go.
4. if they, to stay blue, never attack your teammates, how do they run you off from the spawn? do these 20 people intend to split the ONE scroll they'd sucessfully "steal" from your spawn by coming in and healing your guys but leaving you there to complete the spawn? Wouldn't it be FAR easier if you have this many people to simply swoop in, kill everyone, heal the boss back up, and complete the spawn? It sounds like from your "story" that these are pvm specced mages, and 4-5 half decent pvper's should be able to wipe the floor with them