I think mana is a serious problem right now
with mana pot removed, flask removed, and having corrution pot against long sword+3hp pot is defintely not a great idea.
how are we gonna be able to lane against manaless champions such as tryn renekton mundo zed yasuo katarina shen akali vladmier shyvana lee sin and manymore if we play a champion with mana? whether if they start boot&4pot, longsword&3pot, dorans shied/blade with two pot or cloth armor& 4 pot they still going to outsustain you. so you will be forced to recall before ur enemy because u ran out of mana, your enemy will outfarm u, get more exp and maybe do some dmg on your turret. in some extreme cases when u are back into lane your enemy might already sustain themselves up and ready to stay another round to farm(ie tryn and vlad with built in healing.)
i think this is quite a issue now because in my own experience my teammate or myself with a mana champion often has a hard time against manaless champions due to them being able to stay in lane so long you can never leave lane to roam even when u are ahead and u probably cant kill them unless they make really dumb decisions because they have good sustain and u cant afford the mana to harass them.
something need to be changed now, either some buff to mana pool/regen or nerf the sustain of the manaless champions abit. otherwise mana champions will soon fall out of favour.
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lost the AP it gave.
and you wanna know how to fight them as the other guy will have the ap advantage?
cost has been reduced, you can go with Faerie Charm x2 (or x3) + pots + pink ward, and this start is very doable if you are worried about mana regen, eh