If descent refers to a physical movement downwards:
* Ascent: Moving upwards.
* Rise: Increasing in height or elevation.
* Elevation: The act of raising something to a higher position.
If descent refers to a lineage or ancestry:
* Ascent: Moving upwards in social status, power, or importance.
* Advancement: Progressing to a higher level or position.
* Elevation: Being raised to a higher position or rank.
If descent refers to a decline or deterioration:
* Ascent: Moving upwards or improving.
* Rise: Increasing in value, quality, or importance.
* Improvement: Becoming better or more positive.
If descent refers to a fall from grace:
* Redemption: Being saved or rescued from sin or misfortune.
* Restoration: Returning to a former state or condition.
* Rehabilitation: The process of helping someone to recover from an illness or addiction.
Therefore, the best opposite of descent depends on the specific meaning you intend.