18/20 normal mode has already 619 mobs 230 energy each - 142.370 energy only for this lvl
In an average guild with 50 members each member would have to use 2850 energy only for this lvl - if all members would have 5energy/min they would need about 10 hours (most don't have 5energy/min)

So Gree decided to make the next event impossible to finish without mountains of gems. This kind of high energy LTQ might be ok for individual LTQs where everyone can decide on his own if he wants to spend gems or not but they are really bad for guild LTQs. For the motivation of the team it should be possible to finish - and it should be possible to finish without gems.
I'm pretty sure that most guilds will chancel this LTQ very fast and spend nothing - many members will be upset again which will result in even less participation and gem usage in the next events.