New Blood's effect changes only the text printed on the creature. It can't change words found in abilities it's been granted. For example, if you change Rat to Vampire on Hungry Lynx, your Cats will have protection from Vampires; but if instead you change Rat to Vampire on Phantom Nishoba while you control a Hungry Lynx, Phantom Nishoba will have protection from Rats.

You must choose an existing creature type, such as Vampire or Cat. Card types such as "artifact" can't be chosen.

You choose what word you're changing as New Blood resolves. You don't have to choose a word that appears in the creature's text.

New Blood changes the creature type each time it appears in the creature's type line and/or rules text. It doesn't change the name of the card or any instances of the word being used as part of a card's name.

To pay the additional cost of New Blood, you may tap any untapped Vampire you control, including one you haven't controlled continuously since the beginning of your most recent turn. (Note that tapping the creature doesn't use {T} [the tap symbol].)

You can't choose multiple creature types, such as "Cat Warrior." A Cat Warrior is both a Cat and a Warrior. It's affected by anything that affects either type and unaffected by things that affect non-Cat or non-Warrior creatures.

The type-changing effect can change part of a word (such as "non-Human") if the part of the word is being used to refer to a creature type.

The creature you gain control of won't be a Vampire if you don't choose a creature type in that creature's type line as one to replace.