Ja aber der Trigger von Silas geht ja direkt nach dem Combat damage auf den Stapel, während er selbst erst in den Friedhof geht, nachdem die SBAs gecheckt wurden und den tödlichen Schaden gesehen haben, also hinterher.
Der Silas-Trigger löst beim Zufügen des Schadens aus, geht aber noch nicht auf den Stack. Dann werden SBAs durchgeführt; dabei stirbt Silas. Jetzt gehen alle Trigger, die eben ausgelöst wurden, auf den Stack, und jetzt müssen Ziele angesagt und ggf. weitere Entscheidungen getroffen werden.
Wo steht denn dass SBAs zwischen damage und targets für den Trigger ansagen gecheckt werden?
Ziele werden angesagt, wenn ein Spruch bzw. eine Fähigkeit auf den Stack geht, und das passiert erst nach den SBAs.
117.2a. Triggered abilities can trigger at any time, including while a spell is being cast, an ability is being activated, or a spell or ability is resolving. (See rule 603, "Handling Triggered Abilities.") However, nothing actually happens at the time an ability triggers. Each time a player would receive priority, each ability that has triggered but hasn't yet been put on the stack is put on the stack. See rule 117.5.
117.5. Each time a player would get priority, the game first performs all applicable state-based actions as a single event (see rule 704, "State-Based Actions"), then repeats this process until no state-based actions are performed. Then triggered abilities are put on the stack (see rule 603, "Handling Triggered Abilities"). These steps repeat in order until no further state-based actions are performed and no abilities trigger. Then the player who would have received priority does so.
603.3. Once an ability has triggered, its controller puts it on the stack as an object that's not a card the next time a player would receive priority. See rule 117, "Timing and Priority." The ability becomes the topmost object on the stack. It has the text of the ability that created it, and no other characteristics. It remains on the stack until it's countered, it resolves, a rule causes it to be removed from the stack, or an effect moves it elsewhere.
603.3d. The remainder of the process for putting a triggered ability on the stack is identical to the process for casting a spell listed in rules 601.2c-d. If a choice is required when the triggered ability goes on the stack but no legal choices can be made for it, or if a rule or a continuous effect otherwise makes the ability illegal, the ability is simply removed from the stack.
601.2. To cast a spell is to take it from where it is (usually the hand), put it on the stack, and pay its costs, so that it will eventually resolve and have its effect. Casting a spell includes proposal of the spell (rules 601.2a-d) and determination and payment of costs (rules 601.2f-h). To cast a spell, a player follows the steps listed below, in order. [...]
601.2c. The player announces their choice of an appropriate object or player for each target the spell requires. [...]