What is your favorite ultimate ability for that class?

Prove it...

Learning to read =^^=

Where will the dwarves get summoning magic?

4%. It's quite possible to snatch it.

And why do they need Chaos magic too...?

And indeed, why would a dwarf with an SP higher than their attack need Chaos magic?...
By the way, it's not needed for absolute defense.

Personally, I've come to the conclusion that these two skills are COMPLETELY EQUAL!!! BUT... the ways to achieve them are much easier for the elves.

In total (for the 20th time), Absolute Luck gives 100% double damage. However, all the luck that exists essentially goes nowhere.
Absolute Defense gives 100% damage reduction by 2 and 100% luck block. But no one is stealing the dwarves' luck at the same time.
If you think about it, logistics won't help the Sylvan faction much in battle...