I was playing MtG with a mono red goblin deck, and someone used Virulent Plague on my tokens and they all died! Is there any way to counter this with a mono red card?
Honestly, your options aren't great. Enchantments are a designated weakness for Red, and as such they have basically no options for dealing with them.
If you search on Gatherer for mono-red cards that have "enchantment" in their rules text, you get only 20 results. Of those, 3 have off-color activations, 2 destroy nonenchantments, 2 are Licids (which become enchantments), 3 create enchantment creature tokens (they're from Theros), two are a split card with the enchantment destruction on the white side (Gatherer doesn't really handle split cards very well), one only cares about enchantment creatures, 4 have miscellaneous effects that don't help, and one is Warp World.
The only two cards that might possibly be of use to you are Aura Barbs and Enchanter's Bane. Aura Barbs does a measly 2 damage to your opponent for each Virulent Plague they have (which is terrible), and Enchanter's Bane is only 3 damage a turn, which isn't really a fair trade for shutting down the rest of your deck. Also, Enchanter's Bane is from a Commander deck, so it's not legal in Modern, if that's what you're playing.
If you dig a little broader you can find some other cards that might work, such as Bearer of the Heavens or Capricious Efreet, but they tend to be expensive and/or random in effect, making them pretty useless for your purposes.
The other classic red solution is to simply win the game before the hoser can wreck their field, but a 3 mana enchantment comes down a little too fast for that to be really viable.
If Virulent Plague is a frequent participant of your local metagame, you're probably going to have to splash white or green if you want your token deck to have a prayer.
In addition to the options provided by Arcanist, there is Chaos Warp, which is the common answer to the question of "can red answer enchantments?".
It isn't standard or modern legal, however, and in general red needs to branch out to another colour to be able to interact with enchantments.
Colourless cards, however, are much better at answering enchantments. They're not strictly mono red and are often high converted mana cost (so may not be particularly helpful in your case), but they are castable with just red mana!
There is also the other option of not destroying the enchantment, but instead making use of its effect. Outpost Siege on Dragons would keep you strictly mono red, and allow you still to make use of your tokens if your opponent has a Virulent Plague in play. They'll enter, die immediately, but ping something for 1 on the way out. It has the advantage of being proactive, good in multiples, and you can choose Khans as a card advantage option.
Another option again is to pump your Goblins to be big enough to overcome the effect with the likes of Goblin Chieftain. This is a card you may want to play anyway, but could itself be removed by your opponent to make their Virulent Plague effective again.
Partial answer (I leave the rest to you), your options are -
- Stop Virulent Plague from resolving in the first place. This is of course ideal if you can manage it. The problem is red does not have countermagic, so you'll need to add blue. More seriously, countermagic does not actually win you the game, they only stop you from losing. If your opponent does not draw Virulent Plague then your countermagic might not help you reduce your opponent's life to zero.
- Discard it. This is more proactive than countermagic since you can always cast discard spells. However later in the game they become dead, and more importantly, they cannot stop your opponent from topdecking Virulent Plague. If you go for this route I recommend reading this definitive article on how to use targeted discard. Discard spells are generally black, and you'll need black mana.
- Use an alternative win condition. What this win condition is will depend on the format you're playing and what cards you have available. You're looking for a card that 1) isn't tokens and 2) wins the game, preferably quickly, if unanswered. The standard red cards used in this fashion are Legion Warboss and Goblin Rabblemaster; however both of them rely on tokens, so you're out of luck. It's up to you to find a replacement. I suggest Chandra, Torch of Defiance as a starting point. You could also use something like Glorybringer, which is of course not a goblin, but ignores Virulent Plague.
All three of these plans can work. It's possible you want to use a mixture too, e.g. discard + alternative win condition. It's up to you to explore.