EF_ITEM_BLINK
EF_ITEM_BLINK is defined as 0x100, or 256.
This effect was added to 
Source as a supplement to items on Xbox.
This effects makes an entity have a flashing effect, so that it might be noticed easier.
Usage
In code
Inside of the codebase, effects are defined as a bit-based enum and are stored in m_fEffects. This effect can be manipulated with AddEffects( EF_ITEM_BLINK ), RemoveEffects( EF_ITEM_BLINK ), and SetEffects( EF_ITEM_BLINK ). This effect can be obtained with GetEffects() & EF_ITEM_BLINK or IsEffectActive( EF_ITEM_BLINK ).
In scripting
The functions mentioned above are supported in VScript starting with 
Dota 2 . They can also be found in 
Garry's Mod .
In a map
To use this effect in a map, turn off SmartEdit mode and add the following keyvalue pair to the entity: effects 256.
Note:If it is desired to use this with other effects, you should add the integer value of each effect to the value.You can set the effects keyvalue during runtime using AddOutput with the input value effects x (x being any summation of effects flags to enable).
Warning:Using AddOutput to change an entity's effects may interfere with an entity's simulation functionality.