Spellcaster

Spellcaster is a special ability of some creatures, which enables them to cast a spell during combat. Creatures can cast the spell on their own turn during combat, and typically they use their chance to act to do so. Exceptions:

Enchanters only cast mass spells and they do it in the beginning of their turn and do not lose their chance to attack in the process.
Several creatures cast after an attack.

Perhaps the most renowed spellcasters in Restoration of Erathia version, are the Master Genies, who can cast several different spells. The expansion Armageddon's Blade introduced Faerie Dragons and Enchanters, who also can cast several different spells, as well as Storm, Ice, Energy and Magma elementals, who can each cast protection from their own school of magic.

Can cast instead of normal action:

Archangel – can cast Resurrection once, 100 Health per Archangel in the stack^{*Technically archangels do not cast Resurrection. See Angel and Archangel for more information.}
Master Genie – can cast several different spells at advanced level at 6 power, 3 times, see Master Genie for more information
Ogre Mage – can cast Bloodlust at advanced level at 6 power, 3 times
Storm Elemental – can cast Protection from Air at advanced level at 6 power, 3 times
Ice Elemental – can cast Protection from Water at advanced level at 6 power, 3 times
Energy Elemental – can cast Protection from Fire at advanced level at 6 power, 3 times
Magma Elemental – can cast Protection from Earth at advanced level at 6 power, 3 times
Leprechaun – can cast Fortune at advanced level at 6 power, 3 times
Satyr – can cast Mirth at advanced level at 6 power, 3 times
Faerie Dragon – can cast several different spells at advanced level at 5 * N power, which N is the the number of Faerie Dragons in the stack, 5 times, see Faerie Dragon for more information

Casts before normal action:

Enchanter – can cast several different spells at expert level every 3 rounds at 3 power, see Enchanter for more information

Casts after attack:

Unicorn and War Unicorn - 20% chance to cast Blind at advanced level at 3 power
Black Knight and Dread Knight - 25% chance to cast Curse at advanced level at 3 power
Thunderbird - 20% chance to cast Lightning Bolt, causing 10 * N Damage, which N is the the number of Thunderbirds in the stack^{*Technically Thunderbirds do not cast Lightning Bolt. See Roc and Thunderbird for more information.}
Serpent Fly - casts Dispel at advanced level ^{*Note: Only dispel beneficial spells}
Dragon Fly - casts Dispel and Weakness at advanced level at 3 power ^{*Note: Only dispel beneficial spells}
Sea Witch and Sorceress – casts Weakness at 3 power or Disrupting Ray at basic/advanced level
Mummy - 25% chance to cast Curse at advanced level at 3 power
Fangarm - casts Hypnotize at advanced level for 3 rounds, see Fangarm for more information