Nagas and Serpents you control are Snakes. (We'll errata this to be true.)
Snakes you control have daunt,
deathtouchDeathtouch is a static ability.
A creature with toughness greater than 0 that’s been dealt damage by a source with deathtouch since the last time state-based actions were checked is destroyed as a state-based action. See rule 704.
Any nonzero amount of combat damage assigned to a creature by a source with deathtouch is considered to be lethal damage for the purposes of determining if excess damage is being dealt.
The deathtouch rules function no matter what zone an object with deathtouch deals damage from.
If an object is no longer in the zone it’s expected to be in as an effect causes it to deal damage, its last known information is used to determine whether it had deathtouch.
Multiple instances of deathtouch on the same object are redundant. (CR 702.2), and
poisonousPoisonous is a triggered ability. “Poisonous N” means “Whenever this creature deals combat damage to a player, that player gets N poison counters.” (For information about poison counters, see rule 104.3d.)
If a creature has multiple instances of poisonous, each triggers separately. (CR 702.70) 2. (A creature with daunt can't be blocked by creatures with power 2 or less. Whenever a creature with
poisonousPoisonous is a triggered ability. “Poisonous N” means “Whenever this creature deals combat damage to a player, that player gets N poison counters.” (For information about poison counters, see rule 104.3d.)
If a creature has multiple instances of poisonous, each triggers separately. (CR 702.70) 2 deals combat damage to a player, that player gets two
poison countersA player with ten or more poison counters loses the game. (CR 704.5c).)