how to make tower backdoor?

[reef lagoon]

my creeps:
npc_dota_neutral_kobold
npc_dota_neutral_koboldbaff
npc_dota_neutral_koboldbigboss

[olive crane]

Most likely this way:

1. Remake backdoor from 0 to consider your creeps and rest things

[shrewd venture]

making backdoor should be relatively easy, but I have a question about performance.
how much would searching for all units in range every 0.1s affect the server?
is that even a thing I need to worry about with lua functions?

[olive crane]

Just try and see. There are no profiler or something like that so its impossible to tell how much cpu time it takes relative to server tick. Most likely if your range reasonable (like dota ones) and you don't specify additional useless for your case things like sorting and so on it will not noticable hurt perfomance (you can also always increase tick rate or disable this code to test)

For global range they have special constant and probably optimizations if you need that

[grizzled trail]

From my experience using modifier interval think every 0.1s is pretty fine and not performance heavy if you only search and check for units.