Here's how I would do this:
First I would place a Repeater (under flow) and link it to a Player Iterator and an AI Iterator.
Set the delay on the Repeater to how long in seconds before everything takes damage. Also set it's "infinitely repeat" property to true.
From the Player Iterator, link to a player proxy and damage player.
From the AI Iterator, link to an AI proxy and damage AI.
Then when you want your enemies and players to start taking damage, just start the repeater, for example - when the game starts from a Map object, on match started, start the Repeater.
this is because the activator isn't the Player it is an Ai and an AI can't influence the Player Proxy because it awaits a Player as Input. Just use an
Player Iterator between the Platform and the Player Proxy.
The Disadvantage of an Player Iterator (and also AI Iterators) is that they affect ALL Players on the Map. If you want to hurt a specific Player. You have to store that Player in an Object at spawn and then put that object between the Platform and the Player Proxy
Platform -> get -> stored Object (Player1 for example) -> if get -> Player Proxy (damage)