Direct answer
Do not rely on a single last-minute save. Preserve checkpoints before Act transitions and record the values and character outcomes of the current run; Patch 1.0.10 specifically changed how the Act 3 assessment reads those values.
Build an ending-ready save set
Keep a clean save before the end of each Act and a second save before major personal-quest conclusions. Write down the Sovereign values visible in the current run rather than assuming New Game+ history is still part of the calculation.
Patch 1.0.10 matters
The official patch changed Merlin's Act 3 assessment so it uses the values of the current run instead of accumulated values across the entire save. Older ending discussions may therefore describe behavior that no longer applies.
What this guide will not guess
Official public material confirms branching, rewinds, secrets, and rewritten fate, but it does not publish a definitive ending count or every trigger. Those details stay in the verification queue until reproduced in the current build and independently checked.
Frequently asked questions
How many endings does Sovereign Tower have?
The official sources used here do not state a definitive count, and community counts may combine main, character, and variation outcomes differently.
Does New Game+ history affect the Act 3 judgment?
Patch 1.0.10 says Merlin's assessment should now use the values of the current run, not an accumulation across the entire save.