Sapper Sack is an item that doubles the damage of bombs and replaces all black bombs with red ones; thus, all bombs will deal 4 damage to you when they explode, but will also deal 300 damage to all enemies on the field. This is especially powerful against the final boss, but without proper healing this can end a run very quickly. Going for bomb related relics is tempting because it speeds up the beginning of a run, but getting popping corn will allow you to deal MASSIVE damage with the red bombs and then heal up a bunch of health on the very next turn. This same concept can be applied with wand of skulltimate power but on a smaller scale; rather than relying on upgrading your bombs, you have to focus on upgrading your orbs and hoping they can do splash damage.

tldr: look for sapper sack after first boss, and if you can get it try to build your orbs and relics around bombs. If you can get popping corn and not overdo the bombs you win.