When wearing a tiered leg equipment, the game will check every 2 seconds if a character used a weapon, offensive rune, or offensive spell; if it happened, there is a chance to trigger the effect, which will last for 7 seconds. Note that the Transcendence transformation can not happen while the character is under the effect of the Avatar spell itself. The chances of triggering Transcendence are proportional to the legs' tier:
Source: https://tibia.fandom.com/wiki/Transcendence
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