you want rocket hot, here's two ways.
method #1
Step 1. light a chimney of lump or coshell or whatever you have that will burn hotter than kingsford
Step 2. as its lighting, pour a thin layer of unlit lump into your grill
step 3. when your chimney is ready, pour it over the unlit that is in the grill
step 4. fill the chimney up again with unlit, pour it over the bed of hot coals (a layer of lit between layers of unlit)
step 5. leave the grill lid off and wait 15 minutes
step 6. add another chimney of unlit
step 7. leave lid off for 15 minutes
step 8. add another chimney of unlit
step 9. put on your cooking grate, leave lid open for 10 minutes, then close the lid and wait another 5 minutes.
step 10. OIL YOUR FOOD and cook on your ~900 degree grill
method #2
step 1. light a chimney of lump or something that burns hot.
step 2. put a thick layer of unlit in the grill
step 3. when chimney is ready, pour over unlit
step 4. use some old tongs to gently mix the lit and unlit, try to distribute everything evening
step 5. use a hair dryer or an air pump to stoke the coals for about 5 or 10 minutes. mix again if you need.
step 6. if needed, add another layer of unlit and wait. if not, add cooking grate and sear that tuna.
I've used both methods. Be warned, it will cause porcelain to pop, it will melt OTG and performer lid rollers, it will melt and warp your charcoal grate and burn the seasoning and/or nickel coating off your cooking grate.