Docs/Atom library/Events (WHEN)

Events (WHEN)

Every event atom available in Verse Builder — 46 triggers that wake your rules up.

Last updated 2026-06-06

TL;DR

Events fill the WHEN slot of a rule. Pick the trigger that matches the moment you want your behavior to fire — a player joining, a button pressed, a timer expiring. There are 46 events in total, grouped here by domain.

Auto-generated from the atom registry — what you see here is exactly what the Composer can emit. Each card lists the atom's id (use this in presets and the UI search), the device it targets, the UEFN version range, and every parameter.

💡 Tip

Need a refresher on how rules use events? See The WHEN / IF / DO model.

collectible1

On Collectible Collected

on_collectible_collected

Triggered when an agent collects a collectible object.

Devicecollectible_object_deviceUEFN39.50+

collectibleitem

Parameters

Name	Type	Default	Description
`deviceTag`	string	""	Device Name

combat6

On All Eliminated

on_all_eliminated

Triggered when the configured team runs out of respawns (all members eliminated).

Deviceteam_settings_and_inventory_deviceUEFN39.50+

combatpvpteam

On Eliminated (Victim)

on_eliminated

Triggered when a qualifying elimination occurs. Receives the eliminated agent (victim).

Deviceelimination_manager_deviceUEFN39.50+

combatpvp

On Elimination

on_elimination

Triggered when a qualifying elimination occurs. Receives the eliminator as ?agent.

Deviceelimination_manager_deviceUEFN39.50+

combatpvp

On Enemy Eliminated

on_enemy_eliminated

Fires when a team member eliminates an enemy. Sends the eliminator agent.

Deviceteam_settings_and_inventory_deviceUEFN39.50+

combatpvpteam

On Team Member Eliminated

on_team_member_eliminated

Fires when a team member is eliminated. Sends the eliminated agent.

Deviceteam_settings_and_inventory_deviceUEFN39.50+

combatteam

On Team Member Spawned

on_team_member_spawned

Fires when a team member spawns. Sends the spawned agent.

Deviceteam_settings_and_inventory_deviceUEFN39.50+

combatteam

economy1

On Purchase

on_purchase

Triggered when a player purchases an entitlement. Actions run per change with Change.Change > 0.

UEFN39.50+

economyshop

game-flow2

On Game Start

on_game_start

Triggered when the game experience begins (OnBegin). No external device needed.

UEFN39.50+

game-flowlifecycle

On Round Begin

on_round_begin

Triggered when a new round begins. Useful for multi-round maps.

Deviceround_settings_deviceUEFN39.50+

game-flowlifecycle

interaction1

On Button Press

on_button_press

Triggered when an agent interacts with a button device.

Devicebutton_deviceUEFN39.50+

interactioninput

Parameters

Name	Type	Default	Description
`deviceTag`	string	""	Device Name

item1

On Item Granted

on_item_granted

Triggered when an item is granted to a player via the Item Granter device.

Deviceitem_granter_deviceUEFN39.50+

item

Parameters

Name	Type	Default	Description
`deviceTag`	string	""	Device Name

phase2

On Phase End

on_phase_end

Triggered when a specific phase ends in the phase system.

UEFN39.50+

phasegame-flow

Parameters

Name	Type	Default	Description
`phaseId`	string	""	Phase ID

On Phase Start

on_phase_start

Triggered when a specific phase starts in the phase system.

UEFN39.50+

phasegame-flow

Parameters

Name	Type	Default	Description
`phaseId`	string	""	Phase ID

player2

On Player Join

on_player_join

Triggered when a human player joins the experience.

UEFN39.50+

playerlifecycle

On Player Leave

on_player_leave

Triggered when a human player leaves the experience.

UEFN39.50+

playerlifecycle

pve2

On Guard Eliminated

on_guard_eliminated

Triggered when a guard from this spawner is eliminated. Provides the killer agent (Source) if available.

Deviceguard_spawner_deviceUEFN39.50+

pvenpc

Parameters

Name	Type	Default	Description
`deviceTag`	string	""	Device Name

On Guard Spawned

on_guard_spawned

Triggered when a guard is spawned from this Guard Spawner. Sends the guard agent.

Deviceguard_spawner_deviceUEFN39.50+

pvenpc

Parameters

Name	Type	Default	Description
`deviceTag`	string	""	Device Name

quest1

On Quest Complete

on_quest_complete

Triggered when a quest is completed (tracking variable reaches target value).

UEFN39.50+

quest

Parameters

Name	Type	Default	Description
`questId`	string	"my_quest"	Quest ID

score2

On Score Awarded

on_score_output

Triggered when a player receives score from the Score Manager device.

Devicescore_manager_deviceUEFN39.50+

score

On Score Max Triggers

on_score_max_triggers

Fires when the score manager reaches its maximum trigger count.

Devicescore_manager_deviceUEFN39.50+

score

teleporter2

On Teleported

on_teleported

Fires when an agent emerges from the teleporter after being teleported.

Deviceteleporter_deviceUEFN39.50+

teleportermovement

Parameters

Name	Type	Default	Description
`deviceTag`	string	""	Device Name

On Teleporter Enter

on_teleporter_enter

Fires when an agent enters the teleporter. Sends the entering agent.

Deviceteleporter_deviceUEFN39.50+

teleportermovement

Parameters

Name	Type	Default	Description
`deviceTag`	string	""	Device Name

timer4

On Timer End

on_timer_end

Triggered when a timer device completes successfully.

Devicetimer_deviceUEFN39.50+

timer

Parameters

Name	Type	Default	Description
`deviceTag`	string	""	Device Name

On Timer Fail

on_timer_fail

Triggered when a timer device fails (time runs out without completion).

Devicetimer_deviceUEFN39.50+

timer

Parameters

Name	Type	Default	Description
`deviceTag`	string	""	Device Name

On Timer Urgency

on_timer_urgency

Triggered when a timer device enters urgency mode (near expiration).

Devicetimer_deviceUEFN39.50+

timer

Parameters

Name	Type	Default	Description
`deviceTag`	string	""	Device Name

Repeat Every

repeat_every

Repeats actions at a fixed interval (seconds). Generates a loop with Sleep in OnBegin.

UEFN39.50+

timerloop

Parameters

Name	Type	Default	Description
`seconds`	float	30	Interval (seconds)
`maxRepeats`	int	0	Max Repeats (0 = infinite)

tracker1

On Tracker Complete

on_tracker_complete

Triggered when an agent reaches the target value of a tracker device.

Devicetracker_deviceUEFN39.50+

trackerquest

trade-system4

On Conditional Button Activated

on_conditional_button_activated

Triggered when a conditional button is activated (agent has all required items).

Deviceconditional_button_deviceUEFN39.50+

trade-systemconditional

Parameters

Name	Type	Default	Description
`deviceTag`	string	""	Device Name

On Not Enough Items

on_not_enough_items

Triggered when a conditional button fails because the agent lacks required items.

Deviceconditional_button_deviceUEFN39.50+

trade-systemeconomy

Parameters

Name	Type	Default	Description
`deviceTag`	string	""	Device Name

On Player Reference Activated

on_player_reference_activated

Triggered when a player reference device is activated. Sends the stored agent.

Deviceplayer_reference_deviceUEFN39.50+

trade-systemreference

Parameters

Name	Type	Default	Description
`deviceTag`	string	""	Device Name

On Player Reference Updated

on_player_reference_updated

Triggered when the agent tracked by a player reference device is updated. Sends the new agent.

Deviceplayer_reference_deviceUEFN39.50+

trade-systemreference

Parameters

Name	Type	Default	Description
`deviceTag`	string	""	Device Name

ui7

On HUD Button Click

on_hud_button_click

Triggered when a player clicks a HUD button widget.

UEFN39.50+

uihudinput

Parameters

Name	Type	Default	Description
`buttonWidgetId`	hudButton	""	Button Widget ID

On HUD Message Hidden

on_hud_hidden

Triggered when a HUD message has been hidden from screen.

Devicehud_message_deviceUEFN39.50+

uihud

On HUD Message Shown

on_hud_shown

Triggered when a HUD message has been shown on-screen.

Devicehud_message_deviceUEFN39.50+

uihud

On Popup Button Click

on_popup_button

Triggered when a player clicks a button on a popup dialog. Provides the button index.

Devicepopup_dialog_deviceUEFN39.50+

uipopupinput

On Popup Dismissed

on_popup_dismissed

Triggered when a player dismisses a popup dialog.

Devicepopup_dialog_deviceUEFN39.50+

uipopup

On Popup Shown

on_popup_shown

Triggered when a popup dialog is shown to a player.

Devicepopup_dialog_deviceUEFN39.50+

uipopup

On Popup Timeout

on_popup_timeout

Triggered when a popup dialog times out for a player.

Devicepopup_dialog_deviceUEFN39.50+

uipopup

variable1

On Variable Threshold

on_variable_threshold

Triggered when a variable reaches a threshold value. Supports >=, <=, ==, >, < operators.

UEFN39.50+

variablelogic

Parameters

Name	Type	Default	Description
`variableId`	string	"my_var"	Variable
`operator`	string	">="	Operator
`value`	int	10	Threshold value

zone2

On Zone Enter

on_zone_enter

Triggered when an agent enters a volume device zone.

Devicevolume_deviceUEFN39.50+

zonemovement

Parameters

Name	Type	Default	Description
`deviceTag`	string	""	Device Name

On Zone Exit

on_zone_exit

Triggered when an agent exits a volume device zone.

Devicevolume_deviceUEFN39.50+

zonemovement

Parameters

Name	Type	Default	Description
`deviceTag`	string	""	Device Name

other4

On Chair Exited

on_chair_exited

Triggered when a player stands up from the Chair device. Provides the exiting agent.

Devicechair_deviceUEFN39.50+

Parameters

Name	Type	Default	Description
`deviceTag`	string	""	Device Name

On Chair Seated

on_chair_seated

Triggered when a player sits on the Chair device. Provides the seated agent.

Devicechair_deviceUEFN39.50+

Parameters

Name	Type	Default	Description
`useArray`adv	boolean	true	When enabled, declares chairs as []chair_device array and subscribes/iterates all chairs. Disable for a single chair.

On VFX Disabled

on_vfx_disabled

Triggered when the VFX Spawner effect is disabled. No agent is provided — use with broadcast actions or for_each_player.

Devicevfx_spawner_deviceUEFN39.50+

Parameters

Name	Type	Default	Description
`deviceTag`	string	""	Device Name

On VFX Enabled

on_vfx_enabled

Triggered when the VFX Spawner effect is enabled. No agent is provided — use with broadcast actions or for_each_player.

Devicevfx_spawner_deviceUEFN39.50+

Parameters

Name	Type	Default	Description
`deviceTag`	string	""	Device Name