TickingWithSource is a status property. An effect with this property will "tick" (i.e. apply its effects and reduce its remaining duration by 1 turn) on the turn of the condition's source. Normally, this would happen on the affected creature's turn instead. For example, a target affected by Spirit Guardians (which has the TickingWithSource property) will take damage on the caster's turn, while a target affected by Burning (which does not have the property) will take damage on its turn.
This property is also particularly important for some 1 turn duration effects like Bone Chilled or Ray of Frost. Without this property, these effects would tick down at the start of the target's turn, ending immediately without applying the debuff for even a single turn.
List of conditions with TickingWithSource[edit source]
Affected entity regains 2d8hit points of health every round when below 60 HP. It also receives an additional 3.5 m / 12 ft of movement speed. [See: Bugs]
As part of the challenge to enter the temple, the affected entity has become the target of a chanting cultist, the Farslayer, who can cast Bhaal's Power Word Kill once its profane ritual ends. Exiting the Farslayer's chanting range of 55 m / 183 ft makes you invulnerable to the effect. Slaying the Farslayer stops the ritual and wins the conflict.
Each subsequent turn, if the creature is still touching the metal, the spellcaster can use Reapply Heat Metal to deal another 2d8Fire damage, forcing the creature to pass a Saving Throw again or drop the item (if it is a metal weapon).
The affected entity is attracted to a harpy's luring melody and uses its turn to move closer to the harpy, possibly provoking opportunity attacks from the other harpies.
The affected entity must pass a DC 13 Wisdomsaving throw at the start of their turn or remain lured.
Taking damage or being Shoved removes the condition.