Unique Blood Content

Your blood does not have the hemoglobin associated with most people. A creature that drinks blood like a vampire or stirge that tries to drink yours must succeed on a DC 8 + (IE) Constitution saving throw on a successful bite attack or experience 2 (1d4) poison damage unless otherwise noted and does not receive the restorative benefits from the attack.

• Acid. Your blood is highly acidic. Every minute of exertion, such as combat, a walking forced march, or climbing, you need to succeed on a DC 5 + (IE) Constitution saving throw, increasing cumulatively by 1 every minute of exertion or take one level of exhaustion until taking a short rest. If collected, a flask of 32 ounces equals one use as a weapon. A creature successfully biting you takes 1d(IE) acid damage.
• Chlorocruorin. Your blood is green and processes oxygen better than usual, but you’re sensitive to cold environments. You can hold your breath an additional (IE) × 10 percent. You take an additional (IE) × 10 percent cold damage and have a −(IE) penalty on Constitution saving throws against extreme cold as outlined in official fifth edition sources. When wearing cold weather gear, you must still make this saving throw, although the cold weather gear grants advantage on the saving throw.
• Coboglobin. Your cobalt-based blood is colorless or amber yellow and does not retain oxygen as well. You are also highly susceptible to cold. You can hold your breath (IE) × 10 percent less than usual, and in low oxygen areas like high altitudes, you must succeed on a DC 8 + (IE) Constitution saving throw every hour or take one level of exhaustion until taking a short rest. You take an additional (IE) × 10 percent cold damage and have a −(IE) penalty on Constitution saving throws against extreme cold as outlined in official fifth edition sources. When wearing cold weather gear, you must still make this saving throw, although the cold weather gear grants advantage on the saving throw. You have a +(IE) bonus to saving throws against extreme heat as outlined in official fifth edition sources.
• Combustible. Your blood contains a volatile chemical combination that, when exposed to oxygen by taking piercing or slashing damage, combusts for 1 round, causing (IE)d4 damage to anyone it touches, including you and any creature that causes the damage with a claw or bite attack.
• Erythrocruorin. Your blood, which has a much higher iron content than usual, is much brighter red than is typical and allows you to process more oxygen at a time. You can hold your breath for IE × 10 percent longer than usual and have a +(IE) bonus to Constitution checks related to exertion. If successfully attacked by a creature that sucks blood, the creature gains an additional (IE) benefit from the bite attack and does not take poison damage.
• Hemerythrin. Your blood is colorless or violet, and you heal faster than usual, receiving a + (IE) × 10 percent (minimum 1) bonus to all healing magic, but you process oxygen less efficiently than typical, so you can hold your breath (IE) × 10 percent less than usual, and in low oxygen areas like high altitudes, you must succeed on a DC 8 + (IE) Constitution saving throw every hour or take one level of exhaustion until taking a short rest. You also have a +(IE) bonus to all saving throws against gas-based poison damage.
• Hemocyanin. Your copper-based blood is colorless or blue and operates best in low-oxygen or cold environments. You can hold your breath an additional (IE) × 10 percent. You have a +(IE) bonus to all saving throws against cold damage. You have a −(IE) penalty on saving throws against extreme heat as outlined in official fifth edition sources. In warm tropical environments, every minute of exertion, such as combat, a walking forced march, or climbing, you need to succeed on a DC 5 + (IE) Constitution saving throw, increasing cumulatively by 1 every minute of exertion or take one level of exhaustion until taking a short rest. Because your blood is colorless or nearly so, anyone attempting to stabilize you while you make death saving throws using first aid has a −(IE) penalty on their Wisdom (Medicine) check.
• Vanabins. Your blood color ranges from deep blue to yellow and uses oxygen extremely efficiently. You can hold your breath for IE × 10 percent longer than usual and have a +(IE) bonus to Constitution checks related to exertion. This increase in metabolism, however, requires more food, so you must eat (IE) × 50 percent more food than usual.
• Volatile Liquid. When your blood, which varies from colorless to yellow, is exposed to air, it instantly evaporates into a toxic gas. You are resistant to it but not immune. All within (IE) × 5 feet must succeed on a DC 8 + (IE) Constitution saving throw or take (IE)d4 poison damage.

Real-world Examples

Acidosis; (Found in animals) Hemerythrin, Vanabins, Chlorocruorin, Erythrocruorin, Hemocyanin

Assistive Options

Assistance for these blood types involve avoiding harmful environments when possible.

Magical Assistance

Magic that provides resistance to cold or fire damage will reduce the temperature sensitivities of blood types as applicable by 2 IEs.