Does Convergent Mutation buff units for more than one turn?

No. Convergent Mutation's buff only lasts until the end of the turn it was played — not multiple turns.

The card was errata'd to add "This turn" to its text (October 2025 patch). The original printing was missing that duration, but the errata overrides it for competitive play. The effect expires when the turn ends, and the unit returns to its base Might.