Sometimes it's better to have less cards than more so that you can pull the cards that you want efficiently. It's not strategic to fill your deck completely with all hits either. You're death so most of your spells can heal you back, meaning you don't need to put in heals. It's easier and more strategic to use blades and traps to set up for bigger hits instead of continuously hitting, especially during a boss battle. For mob battles, you can put in a few banshees, vampires and skeletal pirates of your choice, a few death blades, maybe some death traps if you find that necessary, and possibly curses.
For boss fights, put in skeletal pirates because it does the most damage for a level 22 death wizard, a few death blades, death traps, and curses. For the minions in boss fights, keep a vampire or banshee. You do not have a hit all (aoe) spell at level 22 so you need to prepare for multiple hits.
Remember: setting up with blades and traps is important for a death because you do not deal as much damage as some other schools and you do not have hit all spells.