Just as a quick refresher, don't forget you have three distinct attributes to playing a spell/trap/effect card.
1) Trigger. This is when the conditions for the effect are met. I may discard Night Assailant for Monster Recovery, but I don't get to use the effect yet, especially if multiple cards go on the chain.
2) Activation. This is when the effect "begins". You pay any costs required for the activation of the effect immediately. Just like triggers, just because the effect activates, doesn't mean you get to use the effect yet, your opponent has the ability to chain to this activation.
3) Resolution. Ahhh, we FINALLY get to do what the heck the effect says to do on the card. We attempt to resolve the effect and depending on what the effect actually does, we typically wind up a) resolving the effect (returning a flip effect monster from the graveyard to the hand b) negating the effect (via Skill Drain) c) not resolving the effect (the targeted card was removed from play so it can't be revivied d) partially resolving the effect (slightly more complicated issue) or e) resoliving the effect without an action (slightly more complicated issue as well)
Dark World monsters are a great study in setting up this mechanic, because they can trigger at the start of a card resolution (Morphing Jar flip) and then have several outcomes depending on what happens by the time you go to actually resolve their effects, AND in what order.
Lesson to be learned, after a Morphing Jar flip will multiple monsters, make sure your Brron or other DW "non summoning" effect goes first on your chain. Since it'll be the last effect to resolve, they won't be able to stop the special summoning of the more potent ones 8^D