uh well you see it all depends on whether or not riot even likes the concept often time the don't but would still make a similar concept after tweaking out some of its aspects, wait you mean to design the artwork for a concept or create it from scratch?
either way it depends on them
On average how much do concepts artists earn a monthly/yearly?
cant really answer this one again i dont work there.
What is the start of making an art concept?
it all starts with a thought it can be based on anything like the idea for passive/ skill or maybe an image or ability/power this can really be anything all it takes is the idea then build around it fill out the character give it life and make its abilities flow supporting each other or following the primes of the concept eg a girl that controls fire think of what abilities she can have but always try to be unique this is leagues main characterizing theme no 2 champions are the same some may have similar abilities but the way they are used and the other skills that compliment them are always something unique on its own.
How long on average does it take to create a concept?
not very long form the initial thought to the complition of the kit this charactor is already 80% complete the other 20% is additional personality and design.
How important is an art concept to make a finished piece?
depends on weather the art inspired the concept against how dynamic/unique the character looks like i said above this is like 10-5%
How long on average does it take to finish a piece of art?
hmm this question is relative it depends on who draws it and how much time the want to take to create their art.
What are some necessary materials for a concept?
a theme
a back story/lore
a passive
how they interact with other champions(role/basic attack)
and 1-7/8 abilites inclusive of ult (7-8 are really rear cases but its possible if the champion has different forms eg
just once they are not overloaded)
and lastly base stats/damage values the exact numbers can be left out in exchange of %s or using moderate/low/high/massive and over time to describe the amount of damage
hope this helps
[vlad-salute]
nasu010