Regarding the 1-round duration buffs of 4E - it may be that this isn't really something that D&D Next should have in core. Combat is supposed to go much faster, and if you really have so many things to track, it will slow down the game. I expect that D&D Next's "core combat" experience will be with less mechanical detail and depth - that's the way it is right now in the play-test, and I don't expect big changes. Modules can change everything, of course.
So this may be how I'd condense it down:
- Concentration (Sustain)
- Until you cast another spell (similar to concentration, but you can do other things - for something like a Cleric-To-BattleMonster spell)
- Until you make an attack
- Until you move
- Until you save
- Until you take x damage (may allow subcategories, like "until you take 50 fire damage)
- Until you restore hit points (maybe: until you use a hit die)
- Until you take an extended rest
Falling Icicle list isn't bad either, but my list intentionally tries to avoid abstract time units like "encounter". Some people dislike it, and while 4E has the fallback "5 minutes = 1 Encounter", I explicitely want to avoid minutes as well.
Divine Might
You gain +2 to attacks and +1d10 damage to all melee attacks. The spell ends when you cast another spell, take an extended rest or spend a hit die.
Fly
You or the target gain a flight speed of 30 ft. The target keeps flying until you cast another spell, until you take 10 + caster level damage, or until you take an extended rest.
Bestow Curse (Non-Ritual Use)
The target has disadvantage on all attacks, ability checks and saves. It can make a Charisma save at the end of each round to end the effect.
Flaming Sphere
You create a flaming sphere with a 2 ft diameter. It occupies its space and inflicts 2d6 fire damage to anyone ending its turn adjacent to it. A Dexterity Save halves the damage. The spell requires Concentration to maintain. Each round you concentrate on the spell, you can move it up to 30 ft.
Overland Flight
You or the target gain a flight speed of 60 ft. You must concentrate on the spell to maintain it.
Baleful Polymorph
You turn the creature into a toad or similar non-dangerous creature. The spell lasts until you cast another Baleful Polymorph spell. (variant of "cast another spell: Only a specific other spell"). Each time you take an extended rest, the creature can attempt a Charisma save to end the effect.
Summon Monster
You summon a creature to your aid. It lasts until you take an extended rest or until you cast another Summon Monster spell. (another variant of until you cast another spelll - we don't want a zoo. The creature list should make sure having a 24 hour summon isn't unbalanced.)
Resist Elements
Choose one elemental damage type. The target reduces all damage from that elemental type by 10 points. Once the target has absorbed a total of 100 points of damage, the spell ends.
Protection from Elements
The target reduces all damage from elemental damage types by 10 points. Once the target has taken a total of 50 points of elemental damage, the spell ends. (unlike the resist spell, this spell does not track absorbed damage, but the actual taken damage after the resistance was applied. Which version is better, is it a good idea to have both?)
Mage Armor
You gain a bonus to your armor class. The effect lasts until you take an extended rest.
Shield
You gain a bonus to your armor class. The effect lasts until you have taken 10+Caster Level points of damage or until you have taken an extended rest.