A group of friends and I will be beginning a 3.5 campaign in the near future. I have never played 3.5, but would like to use the Blood Mage Paragon Path in the 3.5 campaign. So, is there a prestige class or class that is similar to the 4e Blood Mage Paragon Path in 3.5e, and if not, is there a good homebrew that is similar in theme or mechanics?
I had a quick look for blood magic compatible with 3.5e, and I found, well, a lot of stuff. People seem to like this concept a lot. However, there isn't really a lot of it that seems any good, though. I'll summarize what i've been able to find, and then give some suggestions.
3.5e Material (Non-Homebrew)
Spell Thematics - From Player's Guide to Faerun, this changes your spells cosmetic effects to follow a theme - in this case, i'd say Blood. So instead of sending tiny magic missiles at your foes, you cut open your arm and shoot blood crystals - instead of shooting flame from your hands for Burning Hands, you heat your blood and spray it across your enemies like acid, etc. Just keep in mind it still does the same thing mechanically, it just looks and feels different.
Blood Magus - From Complete Arcane, it's a 10-level prestige class that you can only enter at high level. It has two main problems - 1. It's abilities are very lacklustre and boring. For 10 whole levels, it gives very very little. 2. It can only be entered at level 6, and loses 2 caster levels (i.e. it doesn't advance your spellcasting, meaning you'll be weaker than a wizard/sorc who just goes straight wizard/sorc). This means you can't be a blood mage from level 1 (or even from level 5) and so most of the game will pass with you just being a random wizard, and even as a Blood Magus, most of the time you'll be using spells rather than your crappy abilities.
Wizard or Sorcerer - There are a lot of spells in 3.5e. A lot of them are compiled in the Spell Compendium. A lot of them are bloodish already, or can be made more so with description/personalization/Spell Thematics. A careful spell selection using splatbooks and the Wizard class makes a decent Blood Mage straight out the gate.
Cleric - Only Divine Magic can heal in 3.5e, with some few exceptions. So if you want to be using the power of blood to heal people, you'll need to either multiclass into cleric, or look at an option like Mystic Theurge, gaining access to both cleric and wizard casting.
Tainted Sorcerer - From Unearth Arcana, it's an alternate Sorcerer who gets to use blood as a component in spellcasting. Perhaps go from this into a Blood Mage PrC?
Maho-Tsukai - From Oriental Adventures, the flavour is great, and the mechanics are very simple but work. Basically, you do metamagic, but instead of increasing the spell level, you pay constitution score. Potentially broken, as every way of avoiding metamagic costs are, but if you don't minmax it and just play it as it's intended, very thematic and very cool.
Warlock - From Complete Arcane, refluff the Eldritch Blast as 'Blood Blast', and the rest of their abilities.. fit really well.
Hellfire Warlock - From Fiendish Codex II, it's a prestige class for Warlocks that lets them damage their constitution score to do a lot of extra damage when using an eldritch blast. It's seen as a way to make the generally-low damage of an eldritch blast competitive. Without a way to mitigate the constitution damage (typically a dip into Binder (Tome of Magic) for Naberius' Ability Fast Healing or either a class or feat from Magic of Incarnum to get the Strongheart Vest soulbind to reduce the ability damage to 0), you'll run out pretty fast though.
3.5e Homebrew Material
Blood Mage PrC - Homebrewed for Pathfinder, it appears to be based on the Blood Mage from Dragon Age (also the inspiration for the 4e Blood Mage and the Blood Magus). It seems.. surprisingly good. It gives decent abilities at each level, and doesn't have dead caster levels. The capstone ability seems powerful, but not more powerful than it should be at level 10 of a prestige class. Plus, the abilities are notable (other people will notice them as they have a pronounced effect) and thematic (in the theme of controlling your own and others' blood).
Bloodmage PrC - This is a less interesting blood mage PrC. It adds necromancy, death, and evil spells to player's class list, but player must use hp to cast spells. Can steal hp by sacrificing people, but only to use on blood magic. Can cast spells with expensive components without the components, by sacrificing con score, again can steal con score from people for this purpose by killing them. Boring, crappy, more for a NPC than a PC.
Sanguinist - Crappy clone of blood magus with a decent font. Maybe give it a read, but don't use it.
Blood Magus - Weird but potentially cool. Gives lots of different ways to spend HP to hurt people. Potentially very overpowered, but again, exercise restraint, etc.
Blood Mage - A base class, finally. A wizard, but can spend blood to use the weaker metamagic feats at high levels. I'd just use tainted sorcerer, and avoid this entirely.
Sanguine Master - Pretty cool. A base class that casts spells by using HP, but can't be healed by any kind of magic ever. So he can shoot off a heap of spells, but he'll be weak for days afterwards as he naturally heals up those hp. And getting hit by something is a disaster!
Cursed Blood Scion - This is a stupid thing I wrote to answer a question on this site. Take it for what it's worth.
Overall, i'd be looking at either going Sanguine Master or Tainted Sorcerer or Maho-Tsukai as a base, then MAYBE prestiging into the interesting homebrewed Blood Magus PrC. All those base classes all work, largely due to having full casting. Alternatively, take my vampire knight wannabe class stub and turn it into a full class. Depends what 'kind' of Blood Magus you wanna be, really. All the 'castery' ones are different to what you'd think of as a 'blaster' in 4e, they are more utility problem solvers with nova capability. If you want a 'blaster', homebrewing something for yourself or using a Warlock are pretty much your options.