This works well with cards like Howlpack Resurgence that give your creatures trample
A long time ago, when the only spot removal was Mystical Space Typhoon, Lyla, or Ryko, this wasnt that hard to pull off
Kellan is also good with cards such as Sword of Hearth and Home because he has double strike and can get you multiple triggers per attack
If this card is Normal or Special Summoned (except during the Damage Step): You can Fusion Summon 1 "Magistus" or "Invoked" Fusion Monster from your Extra Deck, using monsters from your hand or field
Getting two shots at it is nice, particularly if you draw and discard a lot of cards
I am shocked these realms went unused, but I guess a lot of the creative process is knowing when to let your favorite ideas go