1) Players have different roles. Instead of everyone doing the same thing at the same time (stack, zerk, kill) as is the case with many bosses, players must simultaneously fight minions to prevent them from entering the portals, construct and repair defenses, and attempt to sever the Marionette’s chains.
2) The roles are mutually reinforcing, and your contribution to any role has an immediate and visible impact on the overall event. The better the defenders do, the more attempts the group gets to sever the chains. The better the attackers do, the fewer attempts are necessary. This mechanism, in my opinion, is VASTLY preferable to an arbitrary countdown timer, as it puts more control in the hands of the players.
3) Despite the large group setting, there is still the opportunity for individual/small group heroism. Splitting the attacking group into five smaller groups, where each small group has to accomplish a task, makes individual contributions matter greatly. Where it’s easy to get lost in a zerg and feel as if your contribution isn’t doing much in the grand scheme of things, it’s obvious that what you do individually matters here.
4) The difficulty is very carefully tuned. Success is definitely possible, but by no means guaranteed. Boss encounters should not be so easy that winning is essentially a guarantee with no effort (see most previous world bosses), but also not be so difficult that they discourage players from future attempts. The Marionette walks that line nicely by providing incremental benchmarks for success – each chain cut is a miniature success on the path to overall success, and even if you fail, it’s easy to imagine doing incrementally better the next time.
5) Rewards scale with performance instead of being all-or-nothing. Even if the overall event fails, you receive some reward for the partial successes you achieved, preventing a failure from being perceived as a total waste of time and thus encouraging players to try again even when success is not guaranteed.
6) This event fosters community. Never have I seen so many map chat messages saying, “We believe in you!”, “You can do it!”, and “Go team! It’s up to us!” And if you ask me, that’s the best part of the whole thing.