These are some ideas I had that could upgrade out of Bumba's mask (fully built tier 2 items). Obviously, you could still buy just Bumba's Mask and sell it later, like normal.
For Physical Only:
Bumba's Crown:
Cost: 2000 (1200)
35 Physical Power
10% Attack speed
10 Mp5
PASSIVE - Your Basic Attacks deal +10 True Damage versus all enemies and your Abilities +10% Damage versus Jungle Camps. You are healed for 10% of a Camp's max health, and if you have an ally nearby, you get the normal gold reward as if you were solo.
For Magical Only:
Bumba's Hood:
Cost: 2000 (1200)
60 Magical Power
15% Cooldown Reduction
20 Mp5
PASSIVE - Your Basic Attacks deal +10 True Damage versus Jungle Camps and your Abilities +10% Damage versus all enemies. You are healed for 10% of a Camp's max health, and if you have an ally nearby, you get the normal gold reward as if you were solo.
For Both Physical and Magical:
Bumba's Helm:
Cost: 2000 (1200)
150 Health
25 Physical Protection
25 Magical Protection
15 Mp5
PASSIVE - Your Basic Attacks deal +10 True Damage and your Abilities +10% Damage versus Jungle Camps. Taking damage from a Jungle Monster increases your physical protection by 10 and your Hp5 by 5 for 5 seconds. Also, 10% of the damage done to you by Jungle Monsters (before mitigation) is reflected back. You are healed for 10% of a Camp's max health, and if you have an ally nearby, you get the normal gold reward as if you were solo.
Shanto's Mask:
Cost: 1800 (1000)
100 Health
5 Hp5
15 Mp5
PASSIVE - Your Basic Attacks deal +25 True Damage and your Abilities +20% Damage versus Jungle Camps. You are healed for 10% of a Camp's max health, and if you have allies nearby, you get the normal gold reward as if you were solo. Also, your basic attacks deal an additional 1 damage and abilities deal an additional 1% damage per stack. You gain 1 stack for every buff wielding monster or mid harpy you kill. No stack limit. Stacks begin counting from the moment you buy Bumba's Mask.