Let's say I have Glissa, the Traitor on my field right now, and my opponent decides to block with two of his smallest creatures and one of his biggest, all at Glissa when she attacks. Since Glissa deals three damage and has first strike, does all three damage have to go to the first creature blocking? Or can I assign one deathtouch damage to each of the blockers?
If I can do the latter, does First strike still apply? I assign the deathtouch damage, and Glissa doesn't take any damage?
If you are attacking you can normally assign damage. First strike means your creature hits first then the opponent creature hits. You can certainly assign only one damage to each creature blOcking as first strike and let the deathtouch abilit kill each creature.
I'm not precise but your first strike death touch creatures lives and kills 2 creatures (if it can assign 2 damge , 1 each creature )
As the attacker, you assign combat damage.
You can assign 1 point of damage to each of the blockers, and as long none of them have indestructibility, or first or double strike, you would be able to destroy all three before Glissa takes any damage.
First strike and deathtouch are static abilities - they are always "active." Glissa, the Traitor always has both first strike and deathtouch.
When an attacker is blocked by multiple blockers, the attacking player chooses the damage assignment order for the blockers (the order that the attacker will deal damage to the blockers in). Lethal damage must be assigned to each creature in the DAO before the next creature can be assigned any damage.
Since Glissa, the Traitor has deathtouch, 1 damage from her is lethal. You may therefore assign 1 damage to each blocker and that will kill all of them.
Since Glissa, the Traitor has first strike, all of her combat damage will be dealt before her blockers (assuming none of them have first or double strike).
Since Glissa, the Traitor has both first strike and deathtouch, any blocker she damages in the first strike damage step will die before it is able to deal regular combat damage to her.