It's hard to find platinum rank videos for Zwei. I thought it was because it's easy to get platinum, but since I got trouble to finish Esonarthex (missed that one pot where you need an upgrade), I decided to record my progress on finishing all dungeons in platinum.

You need 450 hunter rank points to get High Flier. There are 48 stages where you can get the rank from.

Bronze will award you with 7 points.
Silver will award you with 8 points.
Gold will award you with 9 points.
Platinum will award you with 10 points.

Here are the list of the stages (both dungeons and boss fights):

Secundum Mines
Outer Tunnels
Golem Caverns
Illusory Labyrinth: Earth
Magistone Quarry
Spiderweb Burrows
Arch Shelob

Ordium Shrine
Esonarthex
Underground Oratory
Illusory Labyrinth: Water
Aquatic Sanctuary
Path to the Altar
Ephemeroga

Gloomgeld Woods
Vegetable Grove
Monsterville
Illusory Labyrinth: Wind
Golden Quagmire
Umbral Glade
Abyssal Flower

Aurone Forgetower
Tower Foundations
Research Tower
Illusory Labyrinth: Fire
Railroad Station
Blast Furnace
Fafnir

Castle Moonbria
Burial Gardens
Inner Quarters
Waterfall Chasm
Sanctum
Montblanc
Werewolf Dyguld
Fellblade Thermidor

Starry Peak
Training Grounds
Snowstorm Steppe
Sword Shrine Ascent
Kappa's Canyon
Galgarion

Luna Mundus
Lunar Gallery
Dark Alwen
Path of the Chessmaster
Warfiend Dyguld
Sealed Gardens
Marquis Zahar
Trueblood Zahar

S.F. Melzedek
Hall of the Transgressor
Crusader Thermidor
Spiral Nexus
Melzedek Core
Lucian the Gilded

You can get auto platinum for finishing all 4 Illusory Labyrinth and Kappa's Canyon (snowboarding minigame). -> free 50 points

If we account to all that and assume that you get all but the final boss gold medals, that will leave you at:
(42*9)+50 + 7 (finish the final boss)
= 378 + 50+ 7
= 435

This leaves 15 more points to get the High Flier Achievement, which translates to 15 platinums.

I suggest you to get some of the points by refighting these bosses on the colosseum once you are level 30 (or 25+).

• Arch Shelob
  
• Ephemeroga
  
• Fafnir
  
• Montblanc
  
• Werewolf Dyguld
  
• Fellblade Thermidor
  
• Dark Alwen
  
• Marquis Zahar (Vampiric Marquis: Zahar on colosseum)
  
• Warfiend Dyguld

Defeating Fafnir, Fellblade Thermidor, and Warfiend Dyguld might require you to learn the boss attack pattern, so feel free to skip them if you find them hard to beat. For Werewolf Dyguld, you just need to mash him with Ragna's combo attack. Make sure to pump your ATK stat.

You'll need to get the rest of the points from dungeons. I suggest you not to do it in Aurone Forgetower - some levels are just plain annoying. You can also revisit the dungeons once you are high leveled to make it easier. This makes the first few dungeons to be a good source of platinums. These are the levels that I consider to be on the easy - medium difficulty.

• Outer Tunnels
  
• Magistone Quarry
  
• Spiderweb Burrows
  
• Esonarthex
  
• Underground Oratory
  
• Aquatic Sanctuary
  
• Vegetable Grove
  
• Golden Quagmire
  
• Umbral Glade
  
• Inner Quarters
  
• Training Grounds
  
• Lunar Gallery
  
• Path of the Chessmaster

Do not try to get platinum when Alwen is not with you. It's not worth it.

Once you know which levels to clear, feel free to check out the videos below.

I put them in a playlist to make it easier for you to navigate. I also included timestamps for all jars and chests in case you are interested in that.

https://www.youtube.com/playlist?list=PL6jmSkMk6p4Xg4sxd5d2rdKJZeNkYDaaT

All done! It took me a long time to create the timestamp on all videos. At first, I planned to link this video for the boss fights, but that one doesn't seem to be beginner friendly. I mean, they aren't defeating the bosses in a few seconds! So I made one just for this achievement. Hopefully it helps you to get the achievement. I know that I didn't do all bosses, but I hope that the easy bosses will suffice. I got platinum on some bosses by pure luck, and I doubt you can imitate those easily.

High Flying and Hunter's Rank
Zwei: The Ilvard Insurrection Achievement Guide
some questions after finishing the game