#damage assignment

[magicjudge]

I have two attacking creatures: a 4/4 with trample and a 3/3 without trample. My opponent blocks both with Wall of Glare, a 0/5 creature. Do I assign the order in which my creatures deal damage (i.e., can I make it so my trampler tramples through after my other deals 3 to the wall)?

Damage assignment order is only for when a creature is blocking or blocked by two or more creatures. (e.g. Wall of Glare in this scenario). When multiple creatures are assigning combat damage to the same creature, there’s no order to it. The total damage assignment just has to be legal. So yes, you can trample over for 2 here.

[magicjudge]

Regarding cards like Spinebiter that say "You may have Spinebiter assign its combat damage as though it weren't blocked.", when/how is that decision made (after you declare attackers, blockers, any point in combat, etc.)? Also, do you literally just say something like "Spinebiter will just deal all its damage to you [the opponent]"? Thanks!

You decide when you’re assigning its combat damage. You just opt whether or not to assign the damage to the player/planeswalker or the creature blocking it.

[magicjudge]

i have Master Apothecary and two 2/2 bears. my opp. attacks with a 2/3 death touch and i double block to kill it. When the order of damage is decided can i prevent 2 damage to the 1st bear to keep "lethal damaged" from being assigned to my 2nd bear?

No.

Damage assignment doesn’t take damage prevention effects into account when determining what counts as lethal damage. Because the attacking creature has deathtouch, your opponent can still assign 1 damage to each of the blockers to kill the second bear.