1) Enhance 2) Heighten 3) Make powerful 4) Raise 5) To endow with power 6) To enhance 7) To increase the potency 
to use drugs in combination to increase their power
• (v. t.) To render active or potent.
Po·ten'ti·ate transitive verb [ imperfect & past participle Potentiated ; present participle & verbal noun Potentiating .] To render active or potent. Coleridge. 
[v] - increase the effect of or act synergistically with (a drug or a physiological or biochemical phenomenon)