My personal interpretation would be that they passively transcend/evolve constantly and randomly (though always in a beneficial way) due to Eternal Transcendence/Evolution, but they can speed up and direct their transcendence/evolution through combat due to Combative Transcendence/Evolution. When in combat, the transcendence/evolution is faster and the focus of the development is based around the combat. So fighting a magma creature might cause you to transcend heat or evolve heat-resistance.
I feel this interpretation allows both abilities to have their own benefits without either one overshadowing the other.