Guild Wars 2

Does Arcane Resurrection revive speed stack with Rune of Mercy? So with both will it be 20% faster?

It does not. From what I found:

I just tried it during dueling matches, ally would be about 75% hp while downed and i counted the seconds (same healing on either down) and I did not see any noticable difference. both rezzes were between 5/6 second. Hope this helps.