At what points in the game can you activate a legend ability, such as Lee Sin's creature buff ability?

Ruling: Legend abilities follow the same rules as spells regarding timing. If they don't have an "action" or "reaction" tag, they can only be activated during your turn, outside of a showdown.

Sequence:

• Check if the legend ability has an "action" or "reaction" tag
• If no tags are present, it has the slowest activation speed
• Activate only during your turn
• Cannot activate during a showdown

Nuances:

• Lee Sin's ability specifically has no action or reaction tags, making it the slowest kind of activation speed