Having Machete's burn passive work on spell hits isn't a good idea.
The burn passive applying on spell hits dramatically increases the clear speeds for a lot of champions, but clearly favors a lot of the AD casters that are already good in the jungle. Champions with slower clears will get faster clears, but not relative to those with fast clears.
Moving on to having a new AP item, we need an item that better caters to the needs of AP champions as a whole in the mid-game, rather than catering to a certain subset of AP champions in the mid-game. We cannot keep Runeglaive with the new AP item because then the entire AP jungling champion pool will be decided on which item is better.
We also cannot give it a passive that is super useful outside of of the jungle because it will either get abused in lane (like Cinderhulk and Runeglaive were) or it will decide the entire jungle champion pool (like Runeglaive does now). That passive also cannot be a fix-all item for AP jungling concerns like Runeglaive is. It makes nearly every AP champions' jungle clears so fast that clearing isn't a unique strength after Runeglaive is purchased, and restricts the clearing strengths of every champion into the early game. It also solves mana problems extremely well, which is actually really important for jungle diversity, and therefore it is necessary for that to stay.
How do we fix these problems?
We need to give the item good enough stats that any AP champion can afford to buy it without being gimped too hard in terms of the statline. We also need to give the item a jungle-exclusive mana regeneration passive that is as strong as Runeglaive's passive, but is also more universal for more champions. Runeglaive's biggest strength is that its mana regeneration is distributed on a need-by-need basis, and that needs to stay.
Stats can be tuned as needed, so I'll only share my idea of a passive.
Passive: Every time you spend mana, gain some kind of buff, stacking up to three times. Auto attacking a neutral monster consumes the buff to restore 8% missing mana per stack consumed (note: this restores 8% three times, not 24% missing mana). Attacking a champion removes all stacks.
What this passive does is that it is basically an expanded version of Runeglaive's mana regen passive for the jungle that favors a larger subset of AP champions, which ranges from:
-Champions that would want to combo spells tighter than Runeglaive allows (eg. Malzahar)
-Champions that would want to auto attack less than Runeglaive allows (eg. Fiddlesticks)
-Champions that have persistent AoE effects that Runeglaive doesn't apply on (eg. Swain)
-Champions that spam their spells faster than Runeglaive allows (eg. Karthus)
-Champions who already fit with Runeglaive's current mana-restoring casting paradigm (eg. Brand)
What do you guys think of these ideas?
+ 
+ 200g
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+ 
+ 115g
are all textbook examples of champions who, although they may use one of the offensive enchants more effectively for more of the game, can pick Warrior or Devourer based off of when they want to hit power spikes. The number increases if you include champions who are off-meta junglers, like 
and 
, and increases again if you include champions who can decide between one or both of the AD enchants and Cinderhulk, like 
and 
.
Wait, how did i get so much gold from walking?
