I feel the change to Nasus' Q may be a bit too strong. If the change to a flat 20 mana change doesn't work out might i suggest making Nasus' Siphoning Strike return the mana upon killing an enemy unit similiar to how Annie's Disintegrate (Q) works. This might prevent some serious snowballing while still serving the same purpose.

Edit: My thinking is that the change is meant to help early jungling and laning. But Nasus will have basically a trivialized mana cost when he starts getting items, namely glacial shroud, sheen, etc.

Really?

Making it less mana cost wont make nasus become OP and stomp every game.

I actually think Nasus is really strong after he gets 1 or 2 items and his main weakness is early laning/jungling. I think my suggestion would buff Nasus' early game without making his mid-lategame even stronger because i think he's completely fine in those areas.

I just wish it was a flat 20 mana cost yet there was no need to upgrade it, nasus would only have 3 upgradable spells and this would strengthen his late game...

it just works with his kit :\ dunno why they haven't made it this way. I get why veigar and sion do this because their spells actually get significantly stronger but nasus just gets cooldown and i think +100 damage from it.

a good nasus will know how to spend his mana. even if it's at 20, the Q cd will limit it anyway.

The only limiting factor to Nasus' Q farm past level 5 is items. If he hasn't gone back for Philo/Sheen/Something-with-mana then he will run out very quickly, otherwise he can generally sustain for a very, very long time.

Refunding the mana cost would literally make Nasus impossible to remove from lane, as he would just have to build high defense in order to make it impossible to get him away from his farm. No mana items required, and his lifesteal gives him healing for free.

And every time he uses it properly it hits for 3 more damage. Getting levels in it should ensure he can clear an entire creep wave with it. That is 6 last hits, or 18 damage, plus gold from that. That is a really big deal. That is almost two free Long Swords worth 800 gold. And instead of spending any he actually gains gold.

Really shouldn't compare Sion to this, by the way. He is old, broken, and has terrible mechanics and skill synergy. He is either an AP nuker with autoattack spells or an AD carry with minor stun and shield. And his passive is the only RNG left in this game that is still totally borked. He is in dire need of a recreation.