Hello,

recently our clan was about do fulfill one clan achievement level stating 70 Clan XP. We had 844XP prior this achievement, but after that our XP rose to 854.

So either you do wrong calculation, or you are lying about achievement XP and adding just 10 per level (in this case of achievement) to total +70XP for this achievement.

Please make it more clear, state just the increment for current level.

To others: In case of your estimations when you may level up, do not have a much hope, as the leveling (at least via clan achievements) will be negligeable.