Nickaido's here, sorry in the previous chapter I didn't explain about the XP gained per Imperial Ant killed. It's 400 XP and 150 XP for normal Soldier Ant. Alex gained 2100 XP after killing three Imperial Ants and six Soldier Ants, as for Gracier she killed three Imperial Ants (1200 XP) and seven Soldier Ants (1050 XP), a total of 2250 XP, added to the previous XP she leveled up three times. I hope this cleared some of your confusion.
Enjoy!
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Alex was suddenly assaulted by a dreadful feeling as though something powerful was coming in their way. He braced himself and looked in the sky after a second, the incoming monster was indeed powerful, more powerful than the goblin rare species he faced, in terms of the pressure that is. However, having felt Leena's killing intent back then, even if she quickly concealed it, helped him to bear this pressure.