Base Class: Wizard
Having spent most of their time amongst the natural world, a Natural Magician specialises in weaving magic from nature, and incorporating nature's wrath into their spellcasting. They, like Druids, have a strong bond with nature and believe that the four Elements must be kept in equilibrium to keep the world from being destroyed. They make use of both their learnt-Wizard spells and their discovered-Druid spells to protect both the natural world, and the world inhabited around it.
Natural Savant
Your link to the natural world allows you to learn spells from the Druid class. Whenever you gain a wizard level, you can replace one of the wizard spells you add to your spellbook a spell from the Druid spell list. The spell must be of a level for which you have spell slots, and it becomes a Wizard spell for you.
In addition, you know the Druidcraft cantrip and it doesn't count against your number of Wizard cantrips known.
Natural Protection
Beginning at 2nd level, you can call on nature to provide you with a temporary amount of protection. You can use an action to call upon either Thorns of Entanglement or Vines of Almighty Protection, which last for up to 1 minute. You can use this feature once per long rest, or you can expend a spell slot to use this feature again.
Thorns of Entanglement: Working similarly to the spell Entangle, you cause thorns to burst out of the ground in a 10-foot square, or 20x5 foot rectangle, any where within 20 feet of you. For the duration, these plants turn the ground in the area into difficult terrain. A creature in the area when you cast the spell must succeed on a Strength saving throw or be restrained by the entangling plants until the spell ends. A creature restrained by the plants can use its action to make a Strength check against your spell save DC. On a success, it frees itself. After 1 minute, the conjured plants wilt away.
Vines of Almighty Protection: You cause a wall of thickly-intertwined vines and roots to burst out of the ground in a 10-foot high, 10x5 foot rectangular wall directly in front of you. For the duration, this wall provides you full cover. Neither you nor any enemy can see through it, and can you cannot cast spells through it. If you do, you treat the wall as a target of its own. The wall has an AC of 15 and 5 hit points, and has vulnerability to fire damage and immunity to psychic damage. If the wall hasn't been destroyed after 1 minute, it sinks back into the ground.
Natural Thorn
Starting at 6th level, your damaging Druid spells are imbued with your knowledge of spellcasting. When a damaging Druid spell hits, you can add your Intelligence modifier (minimum of 0) to the damage roll.
Summoning Swarm
Beginning at 10th level, you can use a bonus action to summon a magical Swarm of Insects (Monster Manual) that last for up to 1 minute and for that duration, are entirely under your command. You can initially use that same bonus action to command them to attack one target of your choice. On a successful attack, the target must make a Constitution saving throw against your Spell Save DC or be poisoned for the Swarm's duration. The target can repeat the save at the end of their next turns. Once you have used your initial summoning bonus action, you can command the Swarm using any following bonus actions to attack. If the Swarm is not commanded by the summoner, then it will only defend itself.
Naturally Well-Versed
Starting at 14th level, you have studied the magic of the natural world enough to have unlocked new capabilities. Firstly, whenever you level up, you can now replace both Wizard spells with Druid spells, should you wish to. Secondly, choose 3 Druid spells of 3rd level or lower that are in your spellbook. These spells can now be casted with a bonus action, rather than an action. If your spells prevent this from being possible (i.e. all of your spells already have a casting time of 1 bonus action), then either maximise the damage they inflict (1d8 = 8), or increase the range and duration by x0.5 (1 minute = 1.5 minutes; 30 feet = 45 feet).