Shaman talent · row 4 of Restoration, from level 25 (20 with Talented 5/5) · Physical

Tidal Mastery

Increases the critical effect chance of your healing spells by 1/2/3/4/5%.

Game files · build 1.60.1.70291Read straight from the WoW Forever beta client.

Compared with Classic

Classic tooltip

Increases the critical effect chance of your healing and lightning spells by 1%.

What Blizzard said about Tidal Mastery, each line checked against the files.

Matches the files
Tidal Mastery: No longer affects Lightning spells.
The files The tooltip covers healing spells only (Classic: healing and lightning), and the effect's spell mask lost the Lightning Bolt and Chain Lightning bits (1475 to 1472, spell 16194).
Tidal Mastery Class deep dives: Mage and Shaman

69876 Sep 16First beta build we archived. No changes in the client files since.