Each normal mission needs a challenge. Increasing hp doesn't really make things harder, it just makes it more boring. My idea is to put in an extra option after selecting S3 difficulty. Let's call it rank X3. But that's not all, there would be a single player option, 2-3 player and 4-6 player. You can only select one depending on the number of people in your party. NPCs aren't allowed. In this mode, the mobs hit 20% harder and have a slight speed boost. No scape dolls or resurrection are allowed. Dead players are transported back to the lobby while the others try to finish. Successfully finishing allows you/party to get S rank and new rewards.
Each mission will have 3 different types of weapon rewards. 1 striking, 1 ranged, and 1 tech. You can only get one and its random. Each player mode will have different rewards. Clearing it solo will net you a 15* version with buffed stats. 2-3 will net you the basic S rank version. 4-6 reward is an A rank version. An example would be Svaltus sword. The 15* version would have 20% added to it's 0/10 stats. The basic version is as it is. A rank version will be 9* and have stats reduced by 20%. Element is random and probability for good % is good, not 40%s like magana, but more around 30%+. All mp/meseta rewards are still the same.
Best part is they all use existing data so there's no need to download anything.