Thankfully for my sanity, I just checked the template, and it says that most half-trolls were created by magical experimentation. I'm not sure I could've continued playing a game in which something like...THAT...were allowd.
MM V introduced the Xorvintaal Dragon template, which robs a dragon of its spellcasting ability in return for other abilities.
What abilities would those be?
For one, they get the ability to apply the Xorvintaal Exarch template to other creatures, which gives them mostly some decent utility abilities (limited teleport, telepathy witht he dragon and other Exarchs, flight in cooperation with other Exarchs). They can also choose among a list of abilities (one plus another one per two age categories). These include an Alternate Form ability that allows animal forms (okay, so even the Great Wyrm red might be able to change shape), the ability to spend a move action to add 4 dice of damage and +4 DC to their breath weapon, an ability to use a swift action to deal sonic damage equal to half your breath weapon's normal damage, a permanent better Prying Eyes effect, an aura of energy that deals 5 points of damage per age category per turn, and others. Unfortunately, it has no listed LA, so no, you can't pimp your Kobold DFA with it.