It can be used to cripple the infamous spawner strategy, as it damages the troops that spawn out of the buildings, along with the buildings themselves.
All troops from spawners have medium-low health, so the Poison should kill them in a fairly short time.
However, against the Barbarian Hut, the Poison is not effective as it will end before the next wave of Barbarians can be spawned, so time it properly.
As such, the Poison will also affect a Witch in the same way as it affects spawning structures, damaging both the Witch and her Skeletons.
Since the Poison's damage is capable of killing a Musketeer, Wizard, Witch, or Barbarian, but the troop tends to walk out of the radius before it dies, an Ice Golem paired with the Poison to keep the troop inside the radius works well.
A Poison coupled with a Hog Rider is an effective way to deal damage. The Poison will cripple all small units such as Minions and Minion Horde that your opponent plays to counter the Hog Rider.
Pairing Poison with the Bowler is a good idea since the Bowler's knockback can push medium-health swarms back into the poison radius.
The Poison can be used to make your opponent not place small troops inside a radius. This can be useful if you have a Prince or a P.E.K.K.A. charging in.
The description prior to this update was "Covers the target area in a sticky toxin, damaging and slowing down troops and buildings. Remember: solvent abuse can kill!"
On 20/10/16, a Balance Update removed the slowing capabilities of the Poison. This also changed the description. It was used to say: "Covers the target area in a sticky toxin, damaging and slowing down enemy troops and buildings. Yet somehow leaves the grass green and healthy. Go figure!"
On 13/2/17, a Balance Update decreased its duration to 8 seconds (from 10 seconds), but increased its damage per second by 24%.
It uses similar mechanics for its use in Clash of Clans.
Unlike in Clash of Clans, Poison damages buildings too. It also deals a fixed damage per second, unlike in Clash of Clans where it does scaling damage over time. It also does not slow down affected units.
The Poison uses the same deployment and sound animation in Clash of Clans.
The Poison deals damage for a while even if the troop moved out of its range.
It is one of two direct-damaging spell cards that does not contain the phrase "Reduced damage to crown towers." in its description despite dealing reduced damage to Crown Towers, the other being The Log.
The Poison is the only Dark Spell from Clash of Clans to appear in Clash Royale.
However, the Graveyard in Clash Royale resembles the Skeleton Spell in Clash of Clans as they both summon a large amount of Skeletons over time.