Beyond weapons, ammo, health, and armor, Blood features several key items and temporary power-ups that can significantly alter gameplay and provide crucial advantages. These items are often found in secret areas or strategically placed to help you overcome specific challenges.

Key Items:
- Keys (Skull, Spider, Dagger, Moon, Eye): These are essential for progression. Each key unlocks specific doors or mechanisms within a level. You'll often need to find multiple keys to complete a level. They are typically found in heavily guarded areas or as rewards for solving puzzles.
- Flashlight: An inventory item that illuminates dark areas. Essential for navigating dimly lit sections of levels. It has infinite battery in Fresh Supply, but in the original, it had a limited charge.
- Diving Suit: An inventory item that allows Caleb to breathe indefinitely underwater. Invaluable for exploring flooded areas without worrying about drowning.
- Jump Boots: An inventory item that temporarily increases Caleb's jump height, allowing him to reach otherwise inaccessible ledges or platforms.
Power-ups (Temporary Effects):
- Cloak of Invisibility: Renders Caleb invisible to most enemies for a short duration. Excellent for sneaking past dangerous encounters, setting up ambushes, or escaping overwhelming odds. The effect is broken if you attack.
- Invulnerability: Makes Caleb completely immune to all damage for a short duration. Extremely powerful, use it to rush through heavily guarded areas or to tank boss attacks.
- Guns Akimbo: Allows Caleb to dual-wield certain weapons (Sawed-Off Shotgun, Tommy Gun, Flare Gun) for a short duration, doubling their firepower. This is a massive damage boost.
- Death Mask: Temporarily increases Caleb's melee damage, making the Quick Kick much more potent. Less useful than other power-ups, but can be fun for a challenge.
- Reflective Shot: Causes enemy projectiles to reflect back at them for a short duration. Can be devastating against enemies with projectile attacks, especially bosses.
Item Management Tips:
- Conserve Power-ups: Don't waste Invulnerability or Cloak of Invisibility on trivial encounters. Save them for boss fights, large ambushes, or particularly dangerous sections.
- Know Your Keys: Pay attention to which key you need for which door. Sometimes, a key found early in a level is for a door much later.
- use Inventory Items: Don't forget you have the Flashlight in dark areas, or the Diving Suit for underwater sections. They are there to help you.
- Seek Secrets: Power-ups and key items are frequently found in secret areas, making secret hunting even more rewarding.
Mastering the use of these key items and power-ups can turn the tide of battle and help you overcome even the most daunting challenges in Blood.