The gimmick with this artifact is that it consumes twice as much mana, but in a way, it also saves you extra turns. However, until you have a ton of knowledge and artifacts, you'll struggle, especially with a less-than-ideal army.

At the beginning, all races can face challenges; there's no escaping that. Mages, however, have the most knowledge at the start, and it's also what grows the fastest. Usually, there aren't major mana problems. If needed, you might have to spend some time in the city or find a well. Dark mages, on the other hand, have much more trouble with mana. And for tanking damage, there are gargoyles. They may not deal much damage, but they are durable and fast. Single gargoyles can quickly block archers and protect the main units from infantry.
If you want fewer losses, then you should focus on upgrading light magic and building guilds. As you know, light is one of the two native schools for mages, and it will definitely be available in every guild in the city. If you're lucky enough to get regeneration on the second level of the guild, you can play with almost no losses or minimal losses. It can be learned even without having light magic, but with it, it will be much more effective. Also, thanks to the library, you'll have a larger arsenal of spells.