Player Proximity Detector

This script gives all enemies anti gravity while they are chasing the player.

registerType("Enemy")
registerType("PlayerProximityDetector")
registerType("PlayerProximityDetector+ProximityEventEventArgs") -- nested type
registerType("MemeItem")
registerType("Rigidbody2D")
registerType("EventsForModScript")

local worldObj = getCurrentItem().transform.parent
local enemies = worldObj.GetComponentsInChildren(getType("Enemy"))

local proximityDetectors = {} -- so we can unsubscribe in cleanup even on enemies that were destroyed mid game (where .GetComponent doesn't work, but C# PlayerProximityDetector script still exists in memory, so we will store references to those here)
local gravityScalesBefore = {} --dictionary where key is id wihtin level and v

function handleProximityEvent(sender, eventArgs)
    local id = sender.GetComponent("MemeItem").IdWithinLevel
    local rb = sender.GetComponent("Rigidbody2D")
    if eventArgs.ProximityEvent == 1 then -- on start chasing
        gravityScalesBefore[id] = rb.gravityScale
        rb.gravityScale = -0.169
    elseif eventArgs.ProximityEvent == 2 then -- on stop chasing
        if gravityScalesBefore[id] ~= nil then
            rb.gravityScale = gravityScalesBefore[id]
        end -- if nil, it hasn't done anti gravity yet before so don't do anything
    end
end


for i, enemy in ipairs(enemies) do
    local playerProximityDetector = enemy.GetComponent("PlayerProximityDetector")
    if playerProximityDetector ~= nil then
        proximityDetectors[i] = playerProximityDetector
        playerProximityDetector.ProximityEventTriggered.add(handleProximityEvent)
    end
end


function cleanup() -- called when exiting the level
    for i, proxDetec in ipairs(proximityDetectors) do
        proxDetec.ProximityEventTriggered.remove(handleProximityEvent)
    end
end

This might be of use to you:

public enum PlayerProximityEvent
{
    None = 0,
    StartChasing = 1,
    StopChasing = 2,
    StartAttacking = 3,
    StopAttacking = 4,
    StartAnimating = 5,
    StopAnimating = 6,
    StartAudio = 7,
    StopAudio = 8
}

...although the same information can be found in the API reference: