Me Vomiting Ideas

So I'm basically gonna write down a ton of random ideas, please keep in mind that they aren't fully thought through. It's just a giant brainstorm, so here I go

Assassin Item Idea: +85 attack damage active:create a mark on a target champion, after three seconds the mark explodes dealing 20% of the enemy's missing health as magic damage. (note that the enemy will see the mark before it explodes, possible allowing said enemy to back away)

Mage Item Idea: +80 ability power +10% cooldown reduction passive: Abilities deal 3% of enemies' max hp as true damage.

Boots Idea: +45 movement speed passive:reduces all true damage taken by 15%(I would imagine this to be extremely situational)

ADC Item Idea: +35% attack speed +30% critical strike chance +7% movement speed passive: Basic attacks deal 10% more damage to enemies under 40% hp(there might be something like this I'm not aware of)

Mage Item Idea #2: +80 ability power/+250 maximum health. active: Switch between having 80 bonus ability power and 250 bonus maximum health. When switching to bonus maximum health if you are between 75% and 100% of health you will also gain 250 current health(heal basically). If you are between 40 and 74% health you will heal 100 health. If you are below 40% health you will not heal. You will not lose current health switching to ability power. (I know this is really hard to understand) cooldown: 20

Please comment if you find something wrong with one of the following items (you probably will). Or if you think that these are good ideas please give me an upvote. Please give me name ideas and anything else that I'm missing. Thank you!