Umbral Spellportal

Comprising a pair of shadowy mirrors, the Umbral Spellportal links two points on the battlefield, allowing wizards to cast their destructive magics and enchanting boons at incredible distances.

Summon Umbral Spellportal: Eldritch sigils are inscribed into the mist to summon a pair of arcane mirrors, the surfaces of which undulate with shadowy aetheric energy. The spell portals are medium sized floating mirrors who always face eachother. Summon one spell-portal within range where you can see, then summon another spell-portal within 90 feet of the first to a place where you can see. 

Arcane Passage: When looking upon an Umbral Spellportal, those versed in magic see a shadowy reflection of what lies on the other side of its twinned construct; while physical matter cannot travel through the portal, aetheric energy knows no such restriction. Once per round If a spellcaster successfully casts a spell while within 5ft. of each Umbral Spellportal, the range and visibility of the spell can be measured from the other Umbral Spellportal. If a mobile spell effect that isn't a creature such as a flaming sphere, Bigby's hand, watery sphere, spiritual weapon, etc . . . finishes it's movement within 30 feet of one Umbral Spellportal, whomever is controlling that spell may teleport it anywhere within 30 feet of the other Umbral Spellportal.

Empowered by the Shadowfell: In the deceptive realm of the Shadowfell, Umbral Spellportals appear to be everywhere and nowhere all at once. While on the Shadowfell, the second portal can be placed anywhere within 360 feet of the first, instead of 90 feet.