For example if I control Archetype of Finality and I cast Dagger Caster will he get the death touch before his enter the battlefield abilitie?
If so will that mean he will kill everything he deals that 1 damage to?
Yes, Dagger Caster has deathtouch as soon as it exists on the battlefield, and what matters is that it has deathtouch as its ability resolves (after the ability has gone through the stack). Every creature that the ability deals damage to will have been dealt damage by a source with deathtouch and will be destroyed as a state-based action.
To note, if Dagger Caster gets removed from the battlefield before its ability resolves, deathtouch will still work, because then the game will check last-known information about the source of damage and see that it had deathtouch as it last existed on the battlefield. However, if it is Archetype of Finality that gets removed before the ability resolves, Dagger Caster won't have deathtouch as the ability resolves.
I'm a former judge (lapsed), who keeps up to date on rules and policy. Keep in mind that judges' answers aren't necessarily more valid than those of people who aren't judges; what matters is we can quote the rules to back up our answers. When in doubt, ask for such quotes.
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If so will that mean he will kill everything he deals that 1 damage to?
To note, if Dagger Caster gets removed from the battlefield before its ability resolves, deathtouch will still work, because then the game will check last-known information about the source of damage and see that it had deathtouch as it last existed on the battlefield. However, if it is Archetype of Finality that gets removed before the ability resolves, Dagger Caster won't have deathtouch as the ability resolves.