- For the Deltarune monster, see Clover Hydra.
Usage[]
You should try to keep Clover alive through Taunt monsters and Health boosting effects. Solidity and Power are pretty good Artifacts to choose for this.
Try to use Haste or Charge monsters to get your enemies health down to the exact value needed to activate Bullseye on the Rounds.. If you have boosting effects like Shield that can give +1/+1, then that's the perfect tool to nudge down the enemy health just right to get that Bullseye. You may also choose to run a Gemstone-based deck as it synergizes well with Clover's toolkit and can deal necessary chip damage required to trigger Bullseye effects.
Toriel can also help to reduce the enemy ATK so they don't kill your Clover. Especially if she has Taunt through effects like Glad Dummy.
You may also need to nudge up the enemy health a little, too. Madjick is the only card in the game to be able to do this.

Clover's Rounds
PERSEVERANCE or BRAVERY would be best if you want to build a deck around Clover. PERSEVERANCE has Buttercup Treat, which allows you to debuff your Clover to 1 ATK to nudge down the enemy HP for a Bullseye. Your Clover will stay at 1 ATK, as DT monsters are immune to Silence. It also gives your Clover Candy, which allows your Clover to heal itself, which is very good, as you really want Clover to stay on the field to have your Rounds costing 0.
Just be careful of Madjick while using this strategy. If your Clover has 1 ATK and Madjick swaps it around, then your Clover will have 1 HP and that'll be one dead Clover unless you have Taunt monsters.
BRAVERY is also good, as Assault, Rage, Froggit Trio, and Knight's Shield all synergize with Clover.
Assault helps poke monsters to get Bullseye on Rounds, Rage helps poke for Bullseye, and also buffs your monsters, Froggit Trio helps poke, and Knight's Shield gives taunt and HP buff
Countering[]
Ideally, you should be killing Clover as fast as possible. You do NOT want to give them the chance of getting to use multiple rounds for free and potentially even getting a 2nd first round.
If you can't, then try having your monster HP's not align with the health needed to get a Bullseye on that Round, as without Bullseye, the Rounds can't be chained together.
Using a Gaster Blaster is a quick way to rid of an enemy Clover, as Gaster Blasters deal 8 damage, which is enough to kill a Clover without HP buffs in one shot, and ignores Taunt.