Unlike previous tiers, where completing key quests let to an urgent quest, which would unlock more tiers, you're at the end. However, there are still a bunch of key quests for you to complete that will culminate in an urgent quest involving your very first Elder Dragon , so have hope!
Dark Wings, Dark Work
Objective: Hunt a Gore Magala
Location: Jurassic Frontier
Subquest: Wound Gore Magala's feelers
Notes: Gore Magala is the flagship monster of Monster Hunter 4 and wound up as the boss of its offline solo campaign. Here, Gore Magala is the opener for what will be a doozy of a quest tier, so be sure you're prepared. Gore Magala can spread powder from its scales that will infect you, the hunter. Once exposed to the powder (which is inevitable), a blue bar shows up under your name. If it fills to the peak (which takes a very long time), then you will experience debuffs and take more damage. However, if you go on the offensive and manage to land a ton of attacks before that, the effects are reversed and you will have buffs such as increased affinity!
Gore Magala has two stages of rage. The first stage is the traditional rage mode, but on top of that is when Gore Magala will cause the sky to darken, and two strange horns by where its eyes ought to be will become erect. These are its feelers. Gore Magala must be damaged enough to snap out of its second rage mode, and once the mode ends, you cannot hit the feelers anymore, making breaking the feelers a difficult task.
Tigrex by the Tail
Objective: Hunt a Tigrex
Subquest: Mount and topple monster twice
Notes: Tigrex is an incredibly aggressive and brutal Flying Wyvern who favors reckless and powerful charges. When enraged, Tigrex can charge at you up to three times before finally having to stop. Tigrex also has one other special way to damage you: When entering rage mode, Tigrex's roar can actually damage you in addition to sending you flying. Thankfully, the range is very short, so just put some distance between you and Tigrex. And if you have High Grade Earplugs as an armor skill you're completely immune.
Complete this quest plus the 5-star village quest "The Thunderclaw Wyvern" to unlock the 6-star village request "The Hero's Journey".
A Thousand Scales of Dread
Objective: Hunt a Seregios
Subquest: Deliver 1 Wyvern Tear
Notes: Seregios is the flagship monster of Monster Hunter 4 Ultimate and is a Flying Wyvern who specializes in using its hind legs to kick as it flies. Seregios has one other very dangerous trick up its sleeve as well: its ability to cause the Bleeding status. Previously, bleeding was exclusive to Seregios, but Shogun Ceanataur can cause it as well, so you should have some experience with bleeding by now. Seregios can inflict bleeding when it flings its scales at you. If you are hit with the scales as they hit you and when they explode a moment later, you will bleed. If they hit you, but you get out of the way, you won't bleed.
Objective: Hunt a Brachydios
Location: Deserted Island
Subquest: Sever Brachydios's tail
Notes: Brachydios is the flagship monster of Monster Hunter 3 Ultimate and debuted the new slime , since then renamed to Blast. Brachydios's saliva is a brilliant green and will explode shortly after being left on the ground or on you. You'll know if you have Blastblight by seeing a bunch of powder glowing around your body. Roll similar to if you have Fireblight to get it off. If you get hit while you have Blastblight, the slime will automatically explode and you'll be taking a ton more damage. When Brachydios goes into rage mode, the slime it lays on the ground will explode almost instantaneously and it gains a lot of new attacks that are extremely deadly. Note that if you are trying to cut Brachydios's tail, the end weighty bit is hard and will bounce most weapons.
Completion of this quest unlocks the 6-star village quest "Break the Brachydios".
URGENT: Stop the Wheel
Objective: Slay a Shagaru Magala
Subquest: Break Shagaru Magala's horns
Notes: This is it! The Elder Dragon of the offline campaign! Or well, the coolest one anyways. Shagaru Magala has its own area, the Sanctuary. It's a generic one-area map and you cannot return to base camp except by Farcaster, so it's just you, and Shagaru Magala. Unlike Gore Magala, its juvenille form, Shagaru Magala's horns are erect all the time, making them easier to break for the subquest.
When Shagaru Magala enters rage mode, you'll know because it will fly up into the air and roar. Then, random spots on the ground will turn bright purple and then explode. The "randomness" of the spots can be called into question, they have a tendency to follow where your feet are standing. So make sure you pay attention so that you don't constantly get exploded unexpectedly!
Once you complete this quest, you'll be showered with praise...and...another urgent quest?!
URGENT: The Fated Four
Objective: Hunt all large monsters (Gammoth, Astalos, Mizutsune, Glavenus)
Location: Forlorn Arena
Notes: Now this is a real challenge! ...or maybe not. Instead of facing off the monsters two at a time within a one-area map (the Forlorn Arena is basically a reskinned Sanctuary), you'll be facing off with the four flagship monsters one at a time. That makes it that much more manageable, and with four of them to go, the health bars of these monsters is hilariously short. Just make sure you pack supplies for the marathon that this can become. When one monster falls, you'll be given about 45 seconds or so to carve, sharpen, heal up, etc. So you get a small break.
As far as weapon recommendations go, it's hard to say, because Gammoth is weak to fire but Glavenus obviously couldn't care less. Bring whatever you have that has a lot of raw and so long as you are competent at the weapon and keep the offense steady and strong, you will finish within 50 minutes. If you find yourself in a pinch, you might want to bring a Farcaster to warp back to Base Camp for a breather.
Congratulations! You've reached the pinnacle of offline's Low Rank!