Tainted Grail: Conquest

Blood Mages are part of the Moonring faction, so fight like the Summoner and Necromancer through the use of minions, rather than dealing damage themselves. The unique traits of a Blood Mage are that summoning their minions requires them to sacrifice a small amount of their HP each time, 2% of the current max, and that the minions automatically promote and activate themselves at the beginning of and at the end of each turn respectively. Once a minion reaches what would be level 5, they don't promote anymore and instead Overcharge, dying and dealing damage to the enemy. The Blood Mage Ultimate immediately overcharges the selected minion, with a damage buff depending on the level of charge. Charges are gained by sacrificing your HP to use cards. The minions are as follows:


Golem: Attracts all attacks towards itself. Activating the Golem will heal it for the amount shown above its head. Overcharge deals a small amount of damage to the enemy
Fae: Gives you 1 Ultimate charge per Fae level.
Abomination: Deals a single (double at level 4) attack to all enemies. Overcharge deals a powerful attack to all enemies
Wyrm: Deals its level in attacks randomly that also lower enemy Armour by 3 per attack. Overcharge deals a powerful attack to one enemy.

To be successful as a Blood Mage, the idea is to play very, very aggresively, but efficently with respect to minions summoned. Take the automatic summon of a Wyrm, so that you are dealing damage from turn 1 and whenever their are Passive Skills relating to it, take them. The same is true for Abomination related skills, as having both out is more damage being dealt and shorter fights, which means your HP is a lot safer. Also important are skills that increase your health or provide more health/damage/barrier to minions. Promotion cards are not necessary for Blood Mages and can be discarded freely.

Abominations are better to activate when they are a large amount (3+) enemies. Otherwise, stick to using the Wyrm, unless they are drastically different in level. Always activate a Level 4 Wyrm when facing 2 or less enemies, unless you also have a Level 4 Abomination. When it comes to taking Mastery skills, the first set are pretty weak and you can take whichever you think is best, but for the second one at level 20, take the one that makes minions return to level 2 after they overcharge.

The priority for combat is as follows:
Activate Wyrm/Abomination
Place Barrier on Blood Mage
Summon new Wyrm/Abomination
Buff newly placed minions
Summon Golem (situationally, only if you really need it)

If you follow this formula and fight every battle you see, you should reach level 20 in the third area, just before you fight the 3rd guardian.

Good cards to take when you see them are those that allow activating minions, healing the Blood Mage (a White from the Bard heals 10HP once per battle, allowed me to never use a Healing Mixture), giving Barrier and applying damage buffs to minions. Random minion activations can also be good situationally, so take them if there are no other good cards on offer.