this first one I've stated before most likely from a different account that is my brother's
bounty hunting missions
requires that you go on one of the gates and changes for tiers based on rank and you have to go look for a certain monster(s) and beat them or get certain items off them that you could turn in for prestige
*stupid idea onto it - a really hard mission of this and if you actually get the person you're looking for you get $$$ or some CE
monster slayer
have you slay a certain amount of different monster in the arcade in maybe a certain amount of time
Recon missions
This is a stealth based mission and you would be infiltrating a gremlin base/jelly palace/ or a fiends work office It would be like metal gear but you will be forced to equip the recon gear from lock down (or do hard mode and do it with out it..) and this cases you are trying to go against kill enemies because when they see you, you'll need to slay them as fast as you can or else they would run off and bring a unbelievable amount of reinforcements(chance to bring in the green jelly for the jelly palace one) and they could kill you in a few hits or something
Speed run mission
you could be chased by something (from any class really) or a bomb is going to go off(gremlins) or you need to delivered an auto turret to some knights before they are over powered from an enemy surprise attack this would use the speed gear from lock down(I forgot what it is called) or hard mode for more prestige with out it
guardian missions/escort missons
you would have the guardian gear and you have to escort some knights, strangers, or an ally and if they die you would have to use a spark or restart the mission (or they could use the old revive system for this mission) and you get the guardian gear from lock down or hard mode with out it.
Bounty missions sound doable. Would be more something like "Go to this level and return with X items".
Slayer missions sound doable, but would be more of a "Complete this level" opposed to anything else.
Recon missions would be super fun, but current implementation or the suggested version seems a bit... Not Spiral Knights-like. Players should have to scout out levels with nothing but a Recon shield, and maybe some sort of tool gun/autogun. This prevents players from just clearing out levels for money, and makes it so if you're caught you're, well, caught. At the end of the level there is an elevator that brings you to a room full of treasure boxes. This is to make up for the money you didn't get from slaughtering the floor.
Speed run missions should not have you use the striker boost. Players should instead have a long level, similar to after you defeat the battlepod on the second depth of Operation: Crimson Hammer. A long level where players are rushing through an environment would be pretty fun, but I'd prefer it to be more intense by not being able to just zip away from the threats. Also, monsters drop more loot, and there's treasure boxes at the end like the recon mission, however if you're caught in this sort of level you are simply booted back to Haven without any rewards and get the mission failed jingle.
Escort missions already exist in Spiral Knights... The NPCs just are terrible and usually aren't really required to complete the level. No need for a guardian shield.