How can I prevent Anti-planar travel effects from affecting me?

Question

How can a player prevent spells/effects that prevent planar travel in or out of a given area (i.e. Dimensional Lock, Forbiddance, Unhallow, Otiluke's Suppressing Field and, Investiture of the Orthon) from affecting me? Bonus points the lower the level method is.

Answer 1

Iron Heart Surge

The Iron Heart Surge maneuver (Tome of Battle, p. 68) allows you to:

...select one spell, effect, or other condition currently affecting you and with a duration of 1 or more rounds. That effect ends immediately.

This has the advantage of being available at relatively low level (it's a 3rd level maneuver, so typically character level 5 for an initiator class, up to character level 10 with no initiator class levels), and being a very general effect.

The main disadvantage, such as it is, is that many DMs in my experience consider Iron Heart Surge to be too general, to the point of being cheesy. The phrasing "spell, effect, or other condition" is absurdly broad, and note that the effect isn't simply suppressed with regard to you, it's ended entirely. That means that run strictly according to the rules, a 5th level Warblade could have walked into Myth Drannor at the height of its power and BY CROM'd away its protective Mythal.

Additionally, you do need to be affected by whatever you want to remove, which limits its use when what you're trying to do is get into a warded area. For instance, while Iron Heart Surge will work fine to dispel Forbiddance, you have to get into the area affected by Forbiddance to do so, which might defeat the purpose in some cases.

I recommend working with your DM to come up with some sane limits for Iron Heart Surge, that will allow it to keep its function as a "keep bad stuff from affecting me by sheer force of will" power (and perhaps even enhance it, to allow shaking off conditions that prevent taking actions), without allowing the sillier "sneak into places at level 5 and remove area-wide epic spells" usage.

Cheater of Mystra

This combo, originally written up in this old post, combines Antimagic Field with the Initiate of Mystra feat (Player's Guide to Faerûn, p. 81). Initiate of Mystra grants the following benefit:

You can attempt to cast spells even within a dead magic zone or an antimagic field. In a dead magic zone, you must make a successful caster level check against a DC equal to 20 + the level of the spell you are trying to cast. In an antimagic field, you must make a successful caster level check against a DC equal to 11 + the caster level of the antimagic field. If this check is successful, your spell functions normally.

The combo allows you to use Antimagic Field to keep anyone else's spells from affecting you, while still being able to cast spells yourself. Needless to say, this is extremely strong and may cause balance problems in your game. Check with your DM to avoid ruining everybody's fun.

This combo typically becomes available at character level 11, so long as you choose a Cleric domain (such as Magic or Protection) that grants Antimagic Field as a domain spell.

Just dispel it

Most effects that prevent teleportation are spells, and can be dispelled by a bog-standard Dispel Magic or Greater Dispel Magic.

The level requirement of this method depends on the power of the effect you need to dispel, since you'll need to succeed on a caster level check to do so.

Spell Resistance

Dimensional Anchor is blocked by spell resistance, and many other anti-travel effects (Dimensional Lock, Investiture of the Orthon) are explicitly based on Dimensional Anchor and inherit or share this trait. If your spell resistance is high enough, you can just ignore such effects.

Availability depends on the method you use for acquiring spell resistance (some player races, like Drow, get it right at level 1, though this usually comes with level adjustment that isn't worth it).

ABP: Always Be Projecting

Many anti-teleportation measures, like Dimensional Lock and Dimensional Anchor, include the following restriction:

A dimensional anchor does not interfere with the movement of creatures already in ethereal or astral form when the spell is cast

This means a character capable of casting Astral Projection can avoid being trapped by simply never going anywhere in person, and only showing up to dangerous places in astral form. This is a safety measure that is commonly favored by high-level spellcasters anyway, so doing so isn't much of a cost once you're capable of casting the spell.

Needless to say, since Astral Projection is a 9th level spell, this method won't be getting any of those bonus points for being available at low levels.

Freedom of Passage

(h/t Hey I Can Chan)

A rather obscure 8th level Sorcerer/Wizard spell from Polyhedron #159 p. 12 (included in Dungeon #100). This spell allows the caster or a touched target to:

...pass through dimensional barriers, including those created by spells such as forbiddance and dimensional lock, assuming that you possess some means of dimensional travel that would otherwise be blocked by the barrier. The freedom of passage spell also allows you to move freely despite a dimensional anchor spell cast on you.

This spell does require a Githyanki Silver Sword as a material focus, which could be difficult or impossible to obtain, depending on your game, but if you can cast this spell, it's tailor-made to your needs.