Sacrifice

Well, i want to know if i sacrifice a level 2 or more(3,4,5...) agility up in one level 1, this one will get only level 2?
And a skill 1 on skill 1 always give a skill 2?

Regardless of the skill lvl of the monster that is being sacrificed to lvl the skill of a monster you want, the skill lvl always goes up by 1. However, as a monster's skill gets higher, the chances of success get lower, assuming you're trying to use a skill 1 to keep lvling the same monster. If, however, you use a monster with a skill that is higher than 1, your chances of success will increase. Generally, you can safely use skill 1 sacrifices until skill 4-5; after that, skill 4-5 sacrifices are needed. Reportedly, skill 4 sacrifices might fail about 3-4 times between skill 5 and skill 20 on average. I have yet to fail with a skill 5 sacrifice, though, even when sacrificing to a monster that is already maxed level. In my experience, regardless of the skill lvl of a maxed monster, sacrificing anything less than skill 5 will ALWAYS fail (at least it has for me). Sacrificing a skill 5, though, has always succeeded for me, lol.