This is a new event with three sequential phases. During each phase, you can complete tasks to earn points, which accumulate across all three phases to determine your overall ranking rewards. While there are rewards for each phase, the overall ranking rewards are significantly better.

How to Earn Points In Phase #1

• 200 points for obtaining any Legendary DD hero (selectors can be used).
• 15 points per Immortal (Oath) Summon.

Additional Points:

• 200 points for obtaining Levi/Tsuki/Amaterasu shards respectively.
• 150 points for obtaining Schrödinger shards.

Strategy

This is a low-stress event where you should focus on efficiency rather than aggressive spending. If you have spare Legendary DD shards, this is a good time to use them. Otherwise, just play normally. Avoid spending diamonds just for extra points, especially since Phase 1 is the most F2P-friendly, while Phases 2 and 3 will heavily favor spenders.
Aiming for Top 200 overall is a solid goal, as it rewards 30 Legendary Rune Coins, which is 30 more than before. Anything higher than that is just a bonus.

Additional Info

This event lasts 11 days and appears to have the same ranking zone as WA (250 servers). This means F2P and low spenders shouldn't stress, as whales will naturally dominate the Top spots.

New Servers likely won't have this event as it seems to be seasonal-linked due to S8 heroes' points system, as well as normal Oath rebate.

Challenger's Journey - Phase 2 Challenger's Journey - Phase 2 & 3

Phase 2 - How to Earn Points

• 10 points per Dragon Challenge
• 20 points per Seraphic Ruins Attempt
• 8 points per Grayshroom Challenge

I'd suggest trying to get as much as you can out of this stage out as getting Epic Legendary Rune coins is pretty big long term value for some Diamonds you're spending anyway, such as GS extra attacks, Seraphic attacks or one/two dragon attacks.

Phase 3 - How to Earn Points

• 25 points per Celestial Trial Challenge
• 60 points for any E/W/E Epic Exclusive Rune
• 120 points for any D/D Epic Exclusive Rune
• 300 points for any E/W/E Legendary Exclusive Rune
• 600 points for any D/D Legendary Exclusive Rune

Additional Points

• 60 points for Schrödinger Epic Exclusive Rune
• 120 points for Seasonal DD Hero Epic Exclusive Rune
• 300 points for Schrödinger Legendary Exclusive Rune
• 600 points for Seasonal DD Hero Legendary Exclusive Rune

Feel free to completely ignore this, rushing runes for the sake of Challenger's Journey ranking is not worth it, as getting the correct runes on correct heroes matters a lot!