Mana Potions still exist! Sort of...

In the form of Faerie Charms!

Let's take a look at what this item does: Price: 125 gold Effect: +25% Mana Regen Sell: 88 gold

Now, this technique is more cost-effective on champions with a higher base mana regen (because you'll probably only buy them in the early game). Enchanters ( , etc.) are the champions with the highest base mana regen in the game. In the early game, each Faerie charm will grant you roughly 3 mana/5 seconds on these champions. If you buy 2, it's 6 mana/5, and so on.

Mana potions, on the other hand, would grant you 33.3 mana/5 seconds for 15 seconds (100 mana over the time period) for the cost of 35 gold. If mana potions were kept in the game, I'm assuming they would increase in price to 50 gold, along with Health Potions, so I'll work with that number.

For a Faerie Charm to restore 100 mana (on these Enchanters), you would have to have roughly 165 seconds outside of your fountain and below maximum mana. This time period is a full 2 minutes longer than that of a mana potion, but any time spent after that 165 seconds means the Faerie Charm has restored more mana than a mana potion would.

That being said, if you buy 2 Faerie Charms, you only need 82.5 seconds to restore 100 mana. The important thing to remember here is that if you don't end up using Faerie Charms as part of your build, you can sell them back, offering a total net of -37 gold. Mana potions would leave you out 50 gold (or 35 gold back when they were still in the game). If you do end up building it into your kit, you lose 0 gold.

So by spending 250 gold early(what else are you going to spend it on besides Control Wards? And let's be real, no one has all 6 slots filled up early game), you'll get 176 gold back, and you'll slowly reap the rewards throughout the laning phase. Again, this is more a tip tooled towards supports, but hey, certain champions in other lanes can benefit from this as well, if they suffer from low mana pools early.