Can Infernal Tiefling Always Fly? [closed]

One player in a party I’m currently Dm’ing has an Infernal Tiefling Warlock. When he created the character, and up until just shy of level 4 near the end of our gaming session this past weekend, he had the normal walking speed but no flying ability, as is listed in the PHB, if I have it correct.

This past weekend, the party split up. They sent their druid and wizard ahead along a 130 foot, steeply inclined tunnel and through a narrow overhead trap door to cast Gust of Wind in a large, stone cavern. Their reasons for doing so were sound, but unfortunately, in that way, the player characters ended up in two groups. The tunnel separating them was sloped upward so much that each character would have to “climb” to travel through it, as the wizard and druid had had to do.

At that point, the druid, who has always been a very chaotic character, attacked the wizard, who is a good character but a small, female gnome who is often jumped on by the druid. As a result, the druid and the wizard, both still just shy of level 4, began literally fighting in-game: the druid said he was going to wrap the wizard in a web cocoon (he was a giant spider at the time), the wizard made a save and then began casting spells at him to stop him.

The rest of party, made up of five level 3 and 4 characters who are becoming accustomed to these antics from the druid, were just sitting at the bottom of the tunnel for several rounds while the wizard and druid fought. Meanwhile, I had an Ettercap and some giant spiders watching and it seemed like the perfect opportunity to attack – so they did. The wizard was immediately brought to unconciousness because she had already been damaged by the druid.

At that point, the other PC’s got serious and started climbing while the druid was alone with the Ettercap and five giant wolf spiders. I probably sound ruthless at this point but I hadn’t set up the room to kill the party. The fact is, the way they’d split themselves up and then the druid attacked the wizard without even checking the room first, well, that made a very reasonable cavern for a party if 7 level 3 and 4 characters deadly for 2 level 3 characters alone fighting amongst themselves and not paying attention, becoming deadly for the druid and wizard.

After a round of climbing, while the players were scanning their sheets and flipping through various books on the other side of the DM screen, the playet of the Infernal Tiefling Warlock looked up, seeming clearly surprised to me but that’s just me, and said, “Well, I can fly, so I should be able to get up there right away.”

And the druid player, seeming to jump on that, and obviously desperately needing other players up there with him, pulled the book across the table that the Warlock was looking at and said, “He can! It says, ‘Flying Speed 30 feet.”

For the record, in case you’re wondering, it was the Swords of The Coast book and it said the flying ability could only be used if a couple of other things were lost, like Thaumaturgy, for example. I’m not sure of the exact details. I’m the DM but I don’t have a copy of that particular book myself.

Also, for the record, I told the players that I said he could sort of travel upward faster than the other characters and I would think about the flying thing more for later gaming sessions after looking into it.

The PHB lists no flying speed for Infernal Tiefling so I assume the flying ability is an option for a variant version of Infernal Tiefling. Does anyone know? What’s the rule on variants? I want players to have the characters they dream about when they build their characters, but the Warlock player didn’t know about flying before – I’m almost positive he didn’t because tried to climb off a 25 foot pillar and fell two sessions ago. He took minor fall damage and no one said anything about flying. And I’m concerned that if he can fly, it will severely unbalance everything. A warlock who can fly over battles and cast spells down from overhead while remaining out of reach, well, that seems like it has the potential to be extremely over-powered.