The shape of a good open
A strong early build does two jobs at once. It covers the screen with area. It punishes anything that slips through with a tracking hit.
That combination keeps you alive while the gems pile up. Survival early is what lets the build grow.
The loadout
Start with one area weapon as your anchor. Add one weapon that seeks enemies on its own so nothing flanks you.
Then take two passives: one that boosts area, one that boosts projectile count or speed. That is enough to clear your first stage.
Grow it on purpose
From there, level the anchor before adding more. A deep anchor evolves and carries the late game far better than a wide, shallow set.
The evolution mechanics page explains the fusion that turns this base into a late-run weapon.