If dusk loses I cannot learn skills?

I need the spellbook Mass summon poltergeist cubic and it only drops off Gigant Raider. But Gigant Raider only spawns if Dusk wins. Does this mean I cannot ever learn this skill? Dusk never wins.

They are there during competition periods.

yeah i thought that during competition weeks, you get mob type A, B, C, D if dusk wins you get A,B, C, C and if dawn wins you get A, B, D, D. but dawn wins so much, its hard to tell.