The first time someone experiences the Debris Dragon into Dandylion into Black Rose Dragon combo they always question why the Fluff Tokens wouldn't get destroyed. It's happened to me and it's happened to nearly every player I know. Basically it happens like this:
Dandylion + Black Rose Dragon
Dandylion's Effect is mandatory, while Black Rose's is optional. When creating a chain with effects that stack, the mandatory effect(s) will always take place first (Dandylion) followed by any optional effects (Black Rose).
Chain Link 1 = Dandylion (Mandatory)
↓
Chain Link 2 = Black Rose Dragon (Optional)
The chain then resolves backwards—Black Rose Dragon's effect resolves destroying the Field, then Dandylion resolves summoning 2 Fluff Tokens.
Now recently a problem arose with the introduction of Doppelwarrior in Storm of Ragnarok. A handful of players assumed that since Doppelwarrior creates Tokens in a similar manner to Dandylion that any chain involving it would resolve the same way.
Now it is far from the way things actually work. Take the following example:
Junk Warrior + Doppelwarrior
Junk Warrior's effect is mandatory (like Dandylion), while Doppel's is optional (like Black Rose). So just like before, their effects stack and resolve the same:
Chain Link 1 = Junk Warrior (Mandatory)
↓
Chain Link 2 = Doppelwarrior (Optional)
Resolving backwards, the 2 Doppel Tokens are summoned, then the Junk Warrior will gain attack equal to all level 2 or lower Monsters on your side of the Field.
Now let's say someone decided to use both Doppelwarrior AND Dandylion as the Non-Tuners to summon Black Rose Dragon:
Dandylion + Doppelwarrior + Black Rose Dragon
Since Doppelwarrior and Black Rose Dragon are optional, Dandylion must be Chain Link 1.
You can choose the order of Doppel and Black Rose's effects on that chain, but if you are not stupid you'll place Doppel as Chain Link 2 and Black Rose as Chain Link 3.
Chain Link 1 = Dandylion (Mandatory)
↓
Chain Link 2 = Doppelwarrior (Optional)
↓
Chain Link 3 = Black Rose Dragon (Optional)
Simple enough, right?
Keep in mind that Doppelwarrior triggers its effect when it is sent to the graveyard and not upon the successful synchro summon, unlike with Beast of the Pharaoh, so even if the summon is negated you'll still get your Doppel Tokens.
Remember players, the game ends with you.