Uses dark magic (math) to calculate the unit velocity vector that will create a trajectory to your goal given a speed

directionToReachGoal.lua

function calcTrajectoryTheta(start,goal,speed,pickHighAngle)
	local xzStart = start * Vector3.new(1,0,1)
	local xzGoal = goal * Vector3.new(1,0,1)
	local range = (xzGoal-xzStart).Magnitude
	local yDiff = goal.Y - start.Y
	local g = workspace.Gravity
	if range == 0 then return nil end
	if g == 0 then
		return math.atan(yDiff/range) -- simply return angle to the goal
	end
	
	local insideSqrt = (speed*speed*speed*speed) - (g * (g*range*range + 2*yDiff*speed*speed))
	if insideSqrt < 0 then return nil end -- NaN will happen
	
	local sqrt = math.sqrt(insideSqrt)
	
	local angleOne = (speed*speed + sqrt)/(g*range)
	local angleTwo = (speed*speed - sqrt)/(g*range)
	
	angleOne = math.atan(angleOne)
	angleTwo = math.atan(angleTwo)

	if pickHighAngle then
		return math.max(angleOne,angleTwo)
	else
		return math.min(angleOne,angleTwo)
	end
end

function directionToReachGoal(start,goal,speed,pickHighAngle)
	local theta = calcTrajectoryTheta(start,goal,speed,pickHighAngle)
	if not theta then return nil end
	local facingDirection = ((goal-start) * Vector3.new(1,0,1)).Unit
	local facingCFrame = CFrame.new(Vector3.new(), facingDirection)
	local angledCFrame = facingCFrame * CFrame.fromAxisAngle(Vector3.new(1,0,0), theta)
	
	return angledCFrame.LookVector
end

return directionToReachGoal