The phrase "a heavy raid" is correct and usable in written English.
It can be used to describe a significant or intense attack, often in a military or gaming context.
Example: "The enemy launched a heavy raid on our base last night, causing extensive damage."
Alternatives: "a fierce assault" or "a strong attack".
Air raids on Bardia resumed in the lead-up to the ground assault, with 100 bombing sorties flown against Bardia between 31 December 1940 and 2 January 1941, climaxing with a particularly heavy raid by Vickers Wellington bombers of No. 70 Squadron RAF and Bristol Bombay bombers of No. 216 Squadron RAF on the night of 2/3 January 1941.
WASHINGTON, May 2 —The United States has carried out a heavy bombing raid against supply dumps and other targets north of the demilitarized zone in North Vietnam, well‐placed Administration sources said to day.
Richard von Frankenberg told the story of an industrialist who, on leaving Stuttgart after a heavy air raid in the late autumn of 1944, passed on the road a Volkswagen parked high on the city's periphery where its houses and industries were spread out below as in an amphitheater.
The attack came in response to a heavy air raid by Turkish aircraft on PKK bases in the Qandil Mountains in northern Iraq on Saturday – ostensibly part of a new Turkish offensive against terrorist groups, said also to be aimed at Isis.
On the night of 26 27 February, however, the British launched a heavy air raid on the ship.
The Allied naval force off Arawe was subjected to a heavy air raid shortly after the landing.
The Casualty Station suffered a heavy air raid by German forces, with the sterilisation room being destroyed and the camp being hit by numerous bombs.
The commander of the Royal Air Force's Bomber Command, Air Chief Marshal Sir Arthur Harris, also refused to attempt a heavy bomber raid on Tirpitz on the grounds that the Kaafjord area was beyond the effective range of these aircraft and the battleship's guns would cause heavy casualties.
