That progression system really had me stuck for a hot minute. You know, the one where your ghost currency trickles in at a snail's pace unless you dive into the netherworld expeditions? Found out the hard way that hoarding those spectral shards for the 'soul ascension' event is a dead end—the payoff's minimal. Most of my actual level jumps came from grinding the daily rift challenges, even the boring low-tier ones, and fusing duplicate low-star specters for ascension materials. It's a brutal loop, but once you hit Netherworld Citadel Chapter 7, the repeatable dispatch missions start dropping decent gear blueprints. Honestly, I think the game wants you to fail a few boss battles to trigger the pity-rate boosts for higher rarity companions.
Forget about leveling every unit evenly. You'll just stall. I poured everything into my S-tier Lich King summon I got from a free pull, even though his design's kinda generic, and used him to carry three fodder units through resource dungeons. The autoplay function is weirdly inefficient on boss stages with specific mechanics, like the Soulfire Golem's phase shift. Manual play there saved me hours of wasted stamina. Also, joining an active guild, even a semi-casual one, nets you those guild-boss currency exchanges for progression materials you can't get elsewhere. The shop resets weekly, and the good stuff sells out fast.