Spellsword is the Class that specialized in combinations of fast growth (Hist Speaker, Tree Minder, Archein Venomtongue or Support Hist Grove), blood magic experiments (Undead creatures with keyword Drain like Night Shadow, Night Talon Lord and unique Legendaries Blood Magic Lord and Bone Colossus) and good battle strategies (increasing the power of the army by the might of it by Ongoing effect of Divine Fervor and buff from Fifth Legion Trainer after playing another creature, its quantity after playing Scouting Patrol or Imperial Reinforcements).
If you chose Willpower and Endurance attributes you will play this Class. You’ll be able to combine a lot of actions which upgrade the power of your army (playScouting Patrol or Imperial Reinforcements and combine them with Divine Fervor to have passive buffs and with Imprison to destroy enemy creatures) with magic which will give you extra magicka to destroy your enemy as fast as you can (Hist Grove and others). There are a lot of Spellsword cards with Guard (cheap like Kvatch Soldier or expensive like Auroran Sentry). Mantikora is not only a big Guard, but it is a powerful removal card which can destroy an enemy creature. All Guards help you to play against Aggro decks. General Tullius is the great legendary in token decks. And of course there is an unique action Edict of Azura in this class which can destroy enemy Support or creature.
You can play good Midrange decks when you use the cards of this Class. For example:
In this deck you can see mostly 3 and 4 magicka cost minions that is the feature of Midrange decks. There are elements of Token decks there. It means that you can play a lot of creatures and give them all buffs(two Ongoing effects by Divine Fervor). You can also control the board playing combo Imprison + Imperial Reinforcements. The quantity of your army will increase after playing Scouting Patrol or Imperial Reinforcements). There are creatures with Guard (Kvatch Soldier), Drain (Pillaging Tribune) and Prophecy (Midnight Sweep) keywords in this deck.
You can also build more aggressive decks. This is an example of Aggro Spellsword:
This deck has 1,2 and 3 drops but it is weak because if you don’t destroy enemy in the early game you will not win because of failure of late game.
Control Spellsword decks are more powerful and popular:
There are elements of Ramp control deck with Hist Grove, which gives you powerful late game. Also there are strong late game legendaries like Iron Atronach, Nahagliiv and Odahviing, good Prophecy cards to defence (Piercing Javelin or Healing Potion). Shadowfen Priest is unique card that can Silence creature or destroy enemy Support. Edict of Azura can destroy enemy Support or creature.There are some powerful AOEs (Dawn’s Wrath or Immolating Blast) which help you to control the board.
On Arena this class is pretty good. But you must follow magicka curve and potential synergy between cards.