Trinkets are free items that provide vision utility. You start with a Stealth Ward (Yellow Trinket), which places a temporary ward. At level 9, you can upgrade it to either an Oracle Lens (Red Trinket), which sweeps an area for enemy wards and traps, or a Farsight Alteration (Blue Trinket), which places a long-range, visible ward. Your choice of trinket should depend on your role and the game state. Supports and Junglers often swap to Oracle Lens for vision denial, while ADCs might keep Yellow Trinket or swap to Farsight for safer vision placement.

Trinkets: Stealth Ward, Oracle Lens, Farsight Alteration — League of Legends Guide