Combining summoner spells?
I can think of a lot of spells that can have weird combos, which can make certain spells useful again.
= Creates a barrier which heals you over the duration of the shield, if shield breaks the healing is lost. Has less of a shield, but more total health... bonus.
= Deal true damage to a minion then more damage over time.
= more speed, adds a sunfire effect around you dealing true damage.
Any other ones, and thoughts?