been playing mage and his main defensive option early game is flame ward, which quickly becomes to ineffective to keep up with enemy damage, due to it not scaling with his max health by default(needing you to spend a bunch of points to make it scale with missing health, even then capping out at 36% of missing health which is really just another 500 ward, still not enough to help with harder content). The worst part is that due to flame wards bursty nature, it isn’t viable for your main layer of constant sustain and is better as an emergency button.
Or if he specs mana strike to pure ward(which costs a lot of points and the ability to generate mana) he reachs 60 ward per hit, which is about 2/3rds of what you get from shatterstrike, the point and opportunity cost however is heavy and only works in a non mana intensive build. I would also classify this use of mana strike as obscure knowledge as few people use it for ward in their builds.
Then Focus can generate ward but requires that you stand still(which kills you early game) and while it gives you a total of approximatly 100 ward over the second of charging and instantly releasing it, that amount is nowhere near enough to compete with even early game enemies.
Mana spend gained as ward is the best for mana intensive builds but isn’t reliable either as it requires high mana abilities and very rare affixes, thus not being good at all for early or midgame sustain.
Mana gained per second is another rare affix choice, but due to rare affixes it isn’t viable early game. Late game it is 87-189(t5 roll range) per second, while exanguinous does around 400 per second ward at the cost of hp, so the healing is decent… but just not good enough for higher monos. I would just pick exanguinous over using over all those affix slots - but this is about early game ward.
His other sources of ward gen(that create tons of ward) are specific to certain damage skills(like shatter strike) and thus not easily transferable to other builds.
The mage may be able to heal on lightning spells or channelled spells, but he cannot leech health on his fire or cold hit spells - thus he is forced to convert them to lightning if he wants to sustain himself, due to lack of reliable universal ward generation.
This was less of an issue pre-catalyst rework as there was a lot of early ward generation catalysts(now we get a 17 ward per second and need to wait til level 46 before we get a catalyst that generates more ward, most of the ward generation is end game, we need more early game).