anyway, I did a test for all the rest of the runes.
at 1.53 aps, 45 mana regen, -10 soj
start of channel 627 mana end with 103 mana after 10 seconds.
discount of about 6.something mana per second, 2.2 mana per tick.
start of channel 627 mana end with 98 mana after 10 seconds.
also discount of 6.something mana per second.
same mana per tick consumed. but is this the same as the number of stacks/dmg ouput?
nubtro got an analysis here that I don't really understand.
hungry bats and vampire bats very similar to CoB and PB. also about 6.something mana discounted per second. but again I do not know how their damage is counted. is it also by ticks?
direbats different though. it starts at 631 mana and ends with 60 something mana. discount of 2.something mana per second.
probably has to do with this not being a split-tick-spell. its a channeling but one cast spell. that is damage is not split into ticks, but is given out in a single cast.
I'm not sure what the dmg out/stacks are like for the other runes but it seems like apart from direbats, every other rune ticks and consumes mana the same rate. but do they put out damage per tick? I don't know XD.
so direbats seems to fare the worst in terms of FB mana reduction.