4.5 - Hidden Item Interactions

Mages HatInteraction
Working well:
OlafOlaf gains twice the stats and a second cleave
SwainSwain instantly gains double the health and deals double the damage
SivirSimilar to Swain. Sivir will gain double the stats (according to /u/Lethiur1)
EliseElise gains twice the stats and the mana cost increase is affected aswell
OrnnOrnn summons a second elemental roughly after he kicked the first one
DariusDarius will cast his ult a second time. If he kills the unit, he gets his reset and can double ult again (?). Sometimes bugged.
AatroxAatrox will reliably pull the next two targets
RakanRakan will use his ult twice reliable (according to /u/keystone_lite)
ZileanZilean will ult different targets with the second cast (thanks /u/drunkenJanna)
Cant be rated:
ShyvanaShyvana gains double the health and double the damage + DoT but she is stunning herself twice because of her jump
SejuaniDue to long cast time Sejuani seemingly only uses her ult one time (?) Sejuani will cast twice on the same target
Rapid Fire CannonInteraction
Working well:
RakanRakan gains a larger taunt radius benefitting greatly from RFC
NunuNunus Ult has ~the same range as his AA~ global range. Nunu and Willump benefit greatly from RFC due to safer mana gain from AA.
KayleKayles AA range is increased. (Wave doesn’t get larger though)
OlafSimilar to Kayle
AkaliAkalis Ult range scales with RFC. She benefits greatly from RFC
WukongWukongs Ult range scales with RFC. His AA and Ult share the same range.
ZedThough Zed doesn’t have an active Ult, he benefits greatly from RFC for two reasons: He can attack from a safer location/not a lot of running and his AA can’t be dodged, so his proc (every third attack) can’t be denied.
ViVi’s ult range is the same as her AA range
XayahXayah will walk towards the enemies if feathers won’t hit a target (according to /u/Parrichan)
DariusDarius will jump towards the enemies to use his Ult and ends up being in melee range (according to /u/Parrichan)
Not working:
DianaShe will have increased AA but her Ult will not change it’s range (unlike for Titans Resolve). Her Ult will be of no use, unless an enemy walks up to her.
KatarinaApparently similar to Diana. Her Ult range will not increase, rendering her ult sometimes useless (according to /u/ulyssessgrant93 )
AnnieAnnie already has AA range that is similar to her Ult. RFC only increases her AA range, rendering her Ult damage most of the times useless
Lee SinWhile he can kick from distance, the enemy might walk up towards Lee Sin away from the edge, rendering the second part of Lee Sins Ult useless (according to /u/midnightsnipe). /u/THIS_IS_NOT_A_GAME suggest using it with blue buff and duelist, so that he can get his second kick faster
Ruunans HurricaneInteraction
Working well:
KalistaHer spears will hit another target, dealing double the damage. (Also when one target may die due to the spears, the other target will take damage, which can be killed pretty fast)
SamiraSamira’s ult should work with RH (???)
ShyvanaThe on-hit damage and burn gained by Shyvana’s ult is also applied to the RH target
ZedThe AD gained by his passive ult will count towards RH on-hit proc.
EliseElise lifesteal and mana increase debuff is applied by RH.
Spear of ShojinThe unit will gain additional mana as RH counts towards on-hit.
SivirSivirs Ult increases her AD which should aswell increase RH proc dmg (thanks to /u/wing0)
Not working:
OlafOlaf doesn’t gain a second cleave due to RH anymore!
KayleKayle doesn’t proc a second wave with RH
Tryndamere~After Ult his next 3 AA are buffed. (confirmed by /u/ironsundevil)~ 11.5 Patch fixes some kind of interaction

Bonus Tips:

  • (Mage) Brand can make a super good use out of Luden, because it will deal double the damage to CC’d Units and Brands Ult stuns the main target.
  • Sharpshooter gains on-hit effects on their procs. (Spear of Shojin being very strong on carries).
  • Channeled Ult don’t stop while being revived: e.g. ASol will still cast his ult, Kennen will keep going casting his ult etc.
  • Seemingly each of HoJ procs it’s own effect.
  • Trapclaw has a travel time usually rendering it useless against Mage comps (specifically against ASol, he will get his second cast off)
  • Aatrox and Lee Sin in the team will counter each other as Aatrox pulls the farthes unit and Lee Sin kicking the enemy as far away as possible (thanks /u/ulyssessgrant93 ) See also: List of interactions with Mage Cap, Rapid Fire Cannon etc. (r/CompetitiveTFT)

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