Build the link before the fight

0:00–~14:00; especially the first two waves, first recall crash, and any visible 2v2 or jungler window

Start by protecting the bot lane's first wave and level windows. If your ADC can contest the push, keep Bastion linked before a trade and use Dazzle through the ally's position when the enemy steps into a punishable line. After spellcasts, use Bravado attacks only when the enemy cannot freely retaliate; they are your cooldown-and-heal economy. Crash before recalling or roaming. If behind, preserve health and XP, accept lost CS rather than an all-in into a large enemy wave, and use Bastion defensively.

Lane

Trade through the linked ally

If your wave is pushing and your ADC can follow within one screen, use Bastion on the ally who will take the trade, then threaten Dazzle through that ally while Bravado attacks can refresh your spell cycle. If the wave is pushing without vision or your ADC is recalling, crash first and do not turn a short trade into a river walk.

With Taric

• If Taric is your support, use Bastion range as a visible boundary: step forward when you want to contest, but do not force him to follow through fog or across an uncrashed wave. When he casts a spell, his next two attacks are part of his economy, so help him hold space for those attacks instead of abandoning the trade immediately. If you are the ADC, prioritize a wave crash before a recall or roam so Taric's defensive link creates tempo rather than covering a lost lane state.
• If Taric is linked to your engage champion, wait until the entry is real before spending your own gap closer. Taric's spells can cast from the Bastion ally, so a coordinated-looking threat may come from the linked frontliner rather than Taric's body. Keep the enemy in the fight long enough for Bravado attacks and Starlight's Touch charges to matter, but disengage if Taric's link breaks or his carry is no longer close enough to benefit.
• Around an objective, give Taric a clear ally to protect and a safe line to the pit. Crash the nearby wave, reset together, and arrive before spawn so he can use Bastion and Dazzle from prepared positions. If Cosmic Radiance is available, avoid starting a fight at the edge of its range; wait for the enemy to commit into the group, then let Taric cover the actual damage window. After a won fight, move directly to the reachable objective or structure while his protection has created the death-timer advantage.
• If your team is behind with Taric, do not ask him to manufacture a blind engage. Let him protect the player who is still scaling, clear the most dangerous wave, and take a pick only when the enemy is separated or walking into your vision. A safe 5v4 created by a caught target gives Taric a real ultimate window; a forced 5v5 gives the enemy the fight they expect.