If we have archers and the computer only has infantry, then slowing them down is definitely a good strategy. With the large damage range of our archers, we can apply a blessing to them on the next turn. I also often use Bloodlust – it lasts for 3 rounds regardless of magic power, so it works for a Barbarian just as well as for a Warlock!
Haste is an excellent spell, but it requires a certain level of tactical skill.
Of course, Blind and Paralyze are also good options. It would also be good to have healing or at least a spell to remove other spells in our arsenal.
As for spells that deal direct damage, there's Magic Bolt (damage 10 * magic power), Ice Bolt (20 * magic power), and Lightning (25 * magic power).
These are the main spells that are most effective for beginners to use. Of course, there are many others...

Орден Феникса – харизматический :) лидер