raycasting can't give you paths for things it can't see, so it's really limited to being useful for local avoidance. You are going to need a combination of pathfinding and steering to make a moba/rts game.
There are actually surprisingly few good open source pathfinding libraries, and TONS of crap written by people learning how to write pathfinding code. My suggestion would be to just go with recastnavigation. It's pathfinding is great. The only part that's a bit dated is the crowd stuff. It works but it's cpu intensive. You can use it for a moba game, but for an RTS game with a lot of objects, it won't work as it just uses too much cpu.
My preference would actually be to just use an engine like Unity or UDK that already has what you need built in. Even though their pathfinding is loosely based on recast, they provide crowd implementations that are far more performant and can handle much larger crowds.