I don't have the rules in front of me, but with an Evocation Block (or most mundane Blocks) you can generally stop one person from doing anything at all, or a lot of people from doing one thing. The rules are not precise about areas in between, however, such as blocking a few types of actions.
A Veil, of course, is a good example of an Evocation Block which keeps a lot of people from doing one thing (seeing/targeting you).
A Grapple, by counterexample, is a mundane Block which keeps one person from doing just about anything.
There may be some middle ground between the two, such as adding a Zone AoE to the Evocation Block, but it's hard to adjudicate. Common sense would indicate that summoning spirits to harangue everyone you designate as an Enemy requires a lot more finesse than summoning spirits to harangue everybody in a given Zone, but the commensurate cost in shifts would imply that you need to place that on each enemy individually.
One option would be to
1) cast an Evocation Maneuver to place a Sticky Scene Aspect "Spirits Gone Wild"
2) the next exchange, free-tag that to cast an Evocation Block to keep everyone in the Zone from "attacking."
3) if someone finds a way to get around your Block, use Fate Points to Invoke the Spirits Gone Wild Aspect and hope your GM allows you to Invoke-for-Effect/Compel that enemy to not act