No real deaths occur inside a Field of Justice while it is powered by a nexus. Runeterra's magic is quite powerful, and it allows for revival with a minimum of discomfort to the champion.

Then what happens when champion dies just before nexus is destroyed?

I can't exactly remember who said it, but that guy claims that the nexus is bound to another nexus, because it respawns every game.

The summoners feel pain because their minds are directly linked to one another. As is pointed out very poignently in every League Judgement, the inductee must open their mind to being taken control of, or at least guided in some fashion. It's always expemplified with a single line in every Judgement: “How does it feel, exposing your mind?” I think this accurately portrays the idea that both summoner and champion are completely linked, knowing every thought from past and present if they so chose to delve into the recesses of their minds. Pain is also a state of mind, by some beleifs, so it stands to reason that when a champion experiences pain, the summoner feels the backlash of the total mind synchronization they have going on.

As for summoner spawn time? The more powerful you are, the harder it is to rebuild you the same. Simple as that. =)

There's no sense of timing to worry about as far as the Fields of Justice are concerned. A battle arena is powered by a nexus (in come cases, more than one) that is independent of the nexuses used as an objective.

Theoretical, that means that as long as one Nexus remains, both sides could be reanimated. If both however were destroyed, would that mean the Cut of the Cycle ?

Wouldn't the magics of the Fields of Justice just prevent that second nexus from being destroyed, since the battle is suspended once the first one falls? Even if they would go down within seconds of each other one would die first meaning the champions would be raised.

Are you telling me if I found a Nexus and went around doing Un-runeterrian things I could reanimate myself as many times as I wanted?

I'd mention the official definition of necromancy, but pop- culture's changed the direction of it very significantly, so I'm guess I'm cool with that explanation.

Theoretically so, but I'd assume it's really, really hard, otherwise nexuses would be practical nukes.

But, if the writers at Riot Games decide to go in that direction, that's fine too!