based on their lore, responses, or spells?
gravity electromagnetic (force that binds all matter together) weak force strong force (strongest force that allows the core of an atom to exists)
strong force= 
, he hates weak people like his lore shows it, and his only interest is strength like his quotes shows it: "strength above all"
4 is perfection.
he is able to make a gravity field
Syndra Syndra Syndra and Syndra
Gravity would be Sol because stars freaking orbit him.
Electromagnetic might very well be Veigar considering he twists the forces that make up the universe to his will.
No ideas for the other 2.
For those of you who don't know what each force is, here's an handy comic
Hmm an interesting thought experiment, here's what I thought of.
Gravity: toss up between Chogath (grows by eating) or Zac (becomes larger with health) or Syndra (she demonstrates the capacity to manipulate movement)
Electromagnetic: Xerath (he is, more or less, living energy)
Weak force: Bard, Ekko, & Zilean (all 3 are purposely bending a fabric of reality to their whim, causing more entropy)
Strong force: Aurelion Sol (creates celestial bodies & systems)
, all of them
EDIT:
Can you explain weak force?
Gravity - 
- What goes up, must come down
Electromagnetic - 
- I feel as though he might be made up of pure Electromagnetic energy.
Weak force - 
- cause he doesn't do much damage in one burst, but over time he makes you wither away. Like the wind shaping a mountain into an arch.
Strong force - 
- His Ult feels like the strongest force I can think of O_o
- electromagnetic
He binds millions of souls within his lantern holding them all together
Gravity would be Gragas because he can create his own.
The elder dragon
Veigar seems to make sense for gravity. Though I am no physicist. His e is called event horizon. And his W is rather gravity focused.
"In general relativity, an event horizon is a boundary in spacetime beyond which events cannot affect an outside observer. In layman's terms, it is defined as "the point of no return", i.e., the point at which the gravitational pull becomes so great as to make escape impossible, even for light." - Wikipedia
Siphoning power/Glorious Evolution = Strong force
Gravity Field = Gravity
Death Ray = Weak force
Chaos Sorm = Eletromagnetic
fits the deal.
Or not. Depending how you define "magic", that is.
Aurelion Sol, the bastard basically helped form the god damn universe
I nominate Sion for strong force.
So Zileaan would be time. There would be space as well... so... Aurelian Sol? syndra is gravity idk about the whole dar thing. I do like sanji though, and he may marry pudding, and luffy will punch big mom. And kick her with dragon strike.
All the champions = gravity.....
Because they are all bounded in runeterra's gravity field huehuehue
Annie, of course. She domains arcane magic.
