Merge Causality: combine strengths trained on different routesMinor spoilers
Compare stat gains before spending Karma Shards. Train armor on one route and Speed and Resistance on another to make merging worthwhile.
Original video: “Fortune’s Weave: how to merge character stats”; English gaming channel Jay Dunna. Watch the original
Where Merge Causality unlocks
After finishing Parts 1 and 2 and advancing to Part 3, return to the Shrine of Causality. You will find Merge Causality above the obelisk where you previously selected routes. Completed Part 2 stories bring companions into the later stage and provide character versions you can carry forward. You do not need to replay every character’s full route just to make this selection.
Compare merge gains stat by stat
Take 
Alexandra as an example. Her version from 
Theodora’s route may be higher level, while the version trained more on 
Cai’s route has higher Resistance and skill ranks. Expand and compare every category rather than looking only at level.
Merging costs Karma Shards, so what matters is how much it actually improves the character. You can keep training skills in Part 3. Spending shards for a small proficiency increase alone is less appealing.
Train armor and flight on separate routes
Esmeralda already excels in Strength and Defense but lacks Speed and Dexterity. If she stays in armored classes on 
Dietrich’s route, you can try the 
Wing Soldier path on Cai’s route to develop another set of strengths. When the routes converge, merging those two stat profiles offers more than training two similar armored builds.
One point of Luck is not worth three hundred shards
Dante’s trained versions are similar. Start with the strongest version from Theodora’s route; the others mainly offer slightly better casting skills. Another comparison makes the tradeoff clearer:
| Stat increase | Merge cost |
|---|---|
| Luck +1 | 300 Karma Shards |
I would not pay for that single point of Luck. Merge when the routes you have already trained clearly complement each other. If the stats barely change, spend your shards elsewhere.
To improve Resistance and Speed further, you can return to Parts 1 and 2 for another training run. This builds a more rounded character but takes a long time. Set clear goals at the start rather than reaching the merge and discovering that both versions trained nearly the same stats.