Skills Question

Basically I really want to know about what everyone means in trade when they say "Critical Rate Up (4)" or that they have "stacks". I understand the basic for everything else such as people trading multiple crit up cards for multiple other cards, but I'm new to this and would like to understand. I tried sacrificing a monster with a crit up of 2 to a monster with a crit up of 1, but it only increased it's crit up by one. So I'd like to know what the stacks are and how they are beneficial. Thanks!

Stacks increase the probability of success. You can't skill up more than one level at a time (at least not until A Team releases the "skill up" spirit they're supposedly sitting on)

When you are trying to level up skills you sacrifice 1 monster with the same skill to the one you are leveling. If it takes this can only ever raise the skill by one point, never more. The reason players stack skills is that once a skill is leveled to 4 or 5 it is very very hard to get it up higher by sacrificing single skills. The only way to be confident of raising it higher is to trade a higher skill level 'a stack' to it. So to raise a skill form say 7 - 8 I would first using a rank B/B+ or weak A monster, then raise that monsters skill to 4 using single sacrifices of same skilled monsters. Then I would sacrice that level 4 skilled monster 'skill stack' to my main monster I am trying to raise from 7 - 8.

This obvioulsy means that getting your main monster to a skill of 20 will take anything up to 100 sacrifices which is why such a premium is put on monster values where the skill is maxed out.

Fantastic explanation. Thank you very much!