"only XL-2"

Sometimes, it's Berserk + Haste, then running around the battlefield and attacking. If the first speed is present, the enemy might not even get a turn. That's what happened to me with the bears – the opponent couldn't hide one of the snakes, the bears killed it, and then immediately got stunned, giving me a turn and the opportunity to retreat.

As for Blindness, the most brutal option is to cast Blindness, summon all available elementals using all your mana (leaving enough for 3-5 more Blindness spells), then use Wait on all elementals (mandatory), and attack in reverse turn order. The trick is that elementals under Blindness, after using Wait, are also considered to have acted, so they don't get a turn immediately after the Blindness wears off, but wait until all the elementals have had their turn. On the last elemental, cast Blindness again so they don't get a chance. Repeat in the next round. No troops are needed at all; just enough mana and spell points (and first speed).

If you have troops and they are faster than the enemy stack (or you can make them so), then do the opposite – cast Blindness and Haste on the opponent, and Haste/Bless on your desired stacks. Then attack in normal turn order, and cast Blindness again on the last fast stack.

A multi-turn "hit-and-run" strategy with Blindness is also possible. For example, if you have 10 angels, divide them into 1-1-1-1-1-4-1. Use the first angel to remove retaliation, then attack with all of them, and cast Blindness on the last turn. Repeat until the single angels are gone, then deliver the final blow with a powerful attack and retreat. If you have enough mana, you can also reduce the enemy's defense with Disrupt beforehand. In total, you sacrifice 5 angels out of 10, dealing a total of 8+7+6+5+4 = 30 hits from the angels + a powerful attack. This is used when you don't have the opportunity to hit-and-run several times and only have one chance.

An exotic strategy is "drink-and-run" – attack with first speed and 6 units of Witch Covens, cast Blindness, drain all their mana, and retreat.

In general, it's not worth taking risks, and even if all your combat power is concentrated in one stack, it's advisable to add 6 more stacks of "meat" just to prevent the aforementioned tricks from working.