frozen fortress reads "each" doesnt that mean its ttriggers instead of a blanker effect

Yes — it's a triggered ability rather than a static/blanket effect, but "each" isn't what makes it one.

The trigger signal is the "At" clause: "At the start of each player's Beginning Phase" (Rule 383.1 — "at" followed by a point in time during the turn sequence). "Each" is only scope, in two places: "each player's Beginning Phase" means it triggers on both players' turns, and "each unit here" describes what the effect touches. It's still a single trigger producing a single chain item that deals 1 damage to every unit at that battlefield as one instruction — not one trigger per unit.

That distinction matters for reaction timing: because it's one chain item, an opponent can Stupefy a unit in reaction and the damage lands on the reduced Might (FAQ #12274). And since the condition is purely temporal with no "if a unit is here" clause, the ability still goes on the chain at an empty battlefield and the damage instruction simply does nothing (FAQ #12286).