Believing that his recent near-death experience has finally triggered the transformation, Vegeta declares himself a Super Saiyan . He steps forward to challenge Frieza alone, confident that he can now win the fight.
Having realized that Dende is a healer, Frieza targets him first to eliminate the Z-Fighters' support. With a single beam, Frieza kills Dende instantly, leaving the heroes without any way to recover from their injuries. Dragon Ball Z (Dub) Episode 84
" Dende's Demise " (or "Approaching Destruction"). Saga: Frieza Saga (Namek Saga). Believing that his recent near-death experience has finally