MTG: Ruling Help...? General Question about Blocking.?

Deathtouch works both ways both through attacking and blocking as long as its dealing damage so if an opponent had a card that would prevent the damage his card is safe and yes if a card has infect and deathtouch they would both kick in since dealing damage though it wouldn't matter since its going to die due to deathtouch but if the creature the opponent is blocking is indestructable it would still get -1/-1 counters. so simply

Yes its ability still kicks in

Only abilities like Trample do not work if you are defending. Deathtouch works as long as at least one damage is dealt. Infect counters are still applied from a blocking creature. All this only happens if the attacking creature doesn't have first strike or double strike.

First strike has its own attack step so it is possible to kill a creature before it can deal damage.

deathtouch and infect are both static abilites. Static abilities are always active as long as the creature is in the battlefield. Deathtouch turns any damage of a creature with deathtouch into lethal damage, killing the creature dealt damage by it. Blocking creature deals damage to attacking creature in combat step. do the math.

While infect replaces any damage dealt by the creature with infect to -1/-1 counter(to creature) and poison counters(to player).

Yes, the only keyword static ability that does not work when blocking is Trample, because it says so.

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